Description of R11 - with succesfull driver implementation since ROM-WBW 2.5.2


A Version with PAL-replacement of LS-TTL-Logic is in work (not finished before the beginning of 2016)

Now more then 10 PCB of ECB-RAMF R11 in work. This is an mix of the former layout R06 with counter 74HCT4040 and R10 (ATMEL TINY 13, TLC7705), but a fixed physical sector size of 512Byte


File List

FilenameFilesizeLast modified
1n5817.pdf104.9 KiB2015/11/01 02:52
62512_ram_lt-power-on-chips.pdf217.8 KiB2015/11/01 02:52
74hc4040.pdf53.7 KiB2015/11/01 02:52
as6c4008.pdf2.7 MiB2015/11/01 02:53
attiny13.pdf2.9 MiB2015/11/01 02:53
d420625d.pdf111.9 KiB2015/11/01 02:53
ecb-ramf-r11.zip1.4 MiB2015/11/01 02:59
feram_test.jpg84.3 KiB2015/10/31 16:45
fig_10.jpg463.4 KiB2015/10/31 16:46
fig_11.jpg132.7 KiB2015/10/31 16:45
fig_41.jpg21.6 KiB2015/10/31 16:45
fig_42.jpg24.6 KiB2015/10/31 16:45
fig_43.jpg7.4 KiB2015/10/31 16:45
fig_44.jpg37.4 KiB2015/10/31 16:45
fig_45.jpg17.3 KiB2015/10/31 16:45
fig_46.jpg29.7 KiB2015/10/31 16:45
fig_47.jpg11.7 KiB2015/10/31 16:46
fig_51.jpg143.2 KiB2015/10/31 16:46
fig_52.jpg411.5 KiB2015/10/31 16:46
fig_61.jpg534.1 KiB2015/10/31 16:46
fig_62.jpg88.9 KiB2015/10/31 16:46
fig_63.jpg217.5 KiB2015/10/31 16:46
hm6264b.pdf86.6 KiB2015/11/01 02:53
hm628512a.pdf555.9 KiB2015/11/01 02:54
printing_ecb-ramf-r11.sch.pdf279.2 KiB2015/11/01 02:59
printing_ecb-ramf-r12.brd.pdf860.9 KiB2015/11/01 02:59
tl7705.pdf344.7 KiB2015/11/01 03:00


In order to optimize the performance of an ECB-based N8VEM computer, I wanted to design a storage subsystem with the following criteria.

1. A fast storage medium

2. Lower cost

3. Long term stability

For the optimization of working with the ECB N8VEM-computer, I was looking for a fast storage medium like a hard drive is in use, but should not be so expensive, and which may receive its data and buffered.

It is important to note the difference between a RAM DISK and a RAM Floppy.

A RAM disk (also Ramdrive) is a virtual disk and temporary in memory (RAM) of a computer.

A RAM disk is a storage subsystem generally implemented using volatile RAM, sometimes made persistent through the use of a battery, and sometimes not. If the storage is not persistent, then the data will become invalid when the power is turned off.

The benefit of the RAM Disk is the fast access speed. Since it is implemented in memory, access to it occurs at memory speeds and there is no latency or seem time involved. There is also no delay based on the rotational speed of the media. Because of this it´s often referred to as Virtual Memory, although some virtual memory has advanced paging and lookaside capability not addressed here.

The liability with this type of storage subsystem is the volatility of the data should the power by turned off or interrupted by accident.

It is common for small RAM Disks to be implemented by allocating some portion of the processors main ram. A benefit of this is that a modest RAM Disk can be implemented without separate hardware. The liability is that it reduces the amount of main RAM in what may already be a “resource challenged” implementation.

A RAM Floppy on the other hand does not use the local memory resources of the processor, but instead is implemented as an external storage subsystem, which may functionally appear as being similar to a floppy or modest hard drive. As with the RAM Drive, the RAM floppy has efficient access to the storage medium, suffering neither seek-time, latency, nor the delay of rotational media. It is therefore an efficient and expandable storage medium, which may be easily added to an already existing system. It has most of the advantages of a RAM Drive, but not some of the limitation, such as the reduction of available main RAM.

It is mainly used when other physical storage media is placed too slowly or when the computer again, are not available.

Disadvantages of the RAM disk are that the relevant space to free memory, so the operating system and other programs to cache, no longer available. After a reboot of the system (eg after a crash), the contents of the RAM disk generally disappeared (except for reset-proof RAM disks). Because RAM is one of the volatile storage media, if the power supply disappears (eg when switching off) with the memory content and the ramdisk content. Therefore, on the RAM disk should be no important data is stored, unless the uninterruptible power supply to the computer is guaranteed. Should continue before turning off the computer may still be required files are backed up (eg, automated via script). Measured by the price per storage size matters this way to the more expensive storage method.

RAM disks are not to be confused with RAM floppies (like ECB-RAMF). The latter are a more hardware-based replacement for a floppy drive (for example, as a plug-in card) in older or different computer systems. There is not here used by software (driver) is a part of the memory, but a hardware used. They are physical disks and put it in principle rather precursor of Solid State Drives represent.

The result is the ECB-RAMF board, an I/O module, which almost behaves like a mass storage device (HD).

I´ts not similar to the RAM-Drive of the N8VEM-SBC. This is a memory which is mapped with a memory-window-technology into the address space of the Z80.

The memory of the ECB-RAMF has the following features:

- no rotating / moving parts (motor, stepper, etc.)

- no rotating medias

- complete location in I/O-address space

- location on a separate ECB-PCB

- capacity of 4Mbyte which can combined to 8Mbyte by using of a second PCB

- hardware support to realize absolute high speed transfer from / into the main memory with I/O-operations

- avaibility of using DMA to transfer data from / to ECB-RAMF R11

- CMOS-buffering of data via ECB-bus (Lithium battery or NiCd-Accumulator in the ECB-System on the ECB-backplane)

- usablity in combination with other CPU with ECB-Bus

  • f.e. N8VEM SBC V1/V2
  • f.e. N8-2313
  • f.e. SBC 8088
  • etc.

A board was created. Since nothing can be perfect in this world, will have crept in errors here. If you find any, please let me know with a detailed description in N8VEM forum.


Short description of the ECB-RAMF R11 function

The description of the module is used in this document refer to the hardware revision R1.1 Releasedate 15th July 2013. The hardware has been changed to a greater extent and is not compatible with previous version R0.6 (R0.7 as R0.6 with corrections). This is an typical process of Microcomputerdevelopment.

The actual storage media in the RAM Floppy is a collection of eight static RAMs (providing a storage capacity of 4MBytes per board).

The central parts of the assembly are the 8 pieces SRAMs with a maximum total storage capacity of 4 Mbytes on one PCB.

The maximum size of a storage device in CP/M 2.2 is 8Mbyte. The hardware of 2 PCB ECB-RAMF R1.1 can combine together “with software” to one RAM-Floppy with 8Mbyte Data-capacity.

The maximum size of a disk device under CP/M-80 v2.2 is 8MByte. In later versions this limit is much higher.

Our RAM Floppy is idea in that a normal CP/M drive can be implemented using two RAM Floppies providing the total of eight megabytes. One board can provide a smaller but still usable amount of additional fast storage.

In subsequent versions of ECB-RAMF R2.0, the following features are planned:

R2.0 (????)

- An increase in the amount of storage each board can provide, now 8MByte instead of 4MByte.

- Continued ability to use two boards in conjunction to provide additional memory.

  • 8Mbyte on each ECB-RAMF R2.0 with 2 PCB
  • ECB as strictly recommendet standard, no deviations, compliance to KONTRON ECB
  • one PCB for buslogic/businterface and control
  • one Piggyback-PCB only for 8MByte SRAM (maybe SMT)
  • the buslogic/businterface etc. is the same like in R1.1, only 1 internal SRAM-address-line more

After this the development is stopping … otherwise there is in the group interest to realize ECB-RAMF 3.0 with DMA-Access. Maybe…

An addressing logic, which simulates the structure of a hard disk, controls the access to the memory. On the ECB bus are usable:

  • a data port for data traffic between Z80-ECB-bus and 4 MB SRAM to the ECB- RAMF (8-bit bi-directional and usable by OTI/OTIR and INI/INIR)
  • one CMOS-Counter (74HCT4040) controlled by R/W-Access only to the 4MB-CMOS-RAM-Area
  • 2 address registers (74LS374) controlled by two separate addresses in the address area of ECB-RAMF
  • one status port (4-bit input)

The battery backup of the ECB-RAMF is a simple circuit based on conventional Diode- and circuit technology, ensuring that not even go after turning off your N8VEM the information stored in the memory components of the assembly is lost. As of R1.1, this CMOS-buffering-circuit is only usable when the module is not removed from the ECB bus.

Write protection is enable manually by toggling a switch on the board. Up (write enable), Down (write protection)

S2 / JP1 Write-Protection (switch down) – Write-Enable (switch up)

Device status may be observed on three light emiiting diodes as follows…

LED1A (red) display “/PROT”

LED1B (yellow) display “/Option_Bit”

LED1C (green) activity indicator read-write access to data ECB-RAMF

Technical Data

  • PCB-size 160 x 100 mm EUROCARD-Bus-format double-sided with silkscreen
  • ECB-bus (RESET compliant to KONTRON with respect to a modification toN8VEM (usefull modification by jumpers))
  • Switch configuration for /RESET (Kontron, N8VEM, via I/O-port of ECB-RAMF (new))
  • Current consumption max. 800 mA (equipped with LS types and STAM with ca. 60mA per IC), approximately max. 800μA in Power-down mode (this data depends actually on the used type of SRAM)
  • Battery backup (3,6V Lithium type) of the memory modules from outside (ECB-Bus)
  • Write protection (selectable and readable), is important in the use of flash memory, as this the / WR signal is prevented by hardware
  • Use of CMOS RAM 512kByte 8 pieces (K6T4008C1B, HM628512A, AS6C4008) in DIP32-shape (NO SMT)
  • LED-state indicators
    • LED display “activity indicator” based on ATMEL TINY13
    • LED display “/Option_Bit”
    • LED display “/PROT”

Functional description of the ECB RAMF (Rev 11)


block diagram ECB-RAMF R11

Description of the block diagram

The maximum storage capacity of the ECB board ECB-RAMF 11 is 4 MB, but each of the 8 SRAM IC 512kByte must be equipped on the PCB. Addressing the 4 MB is calculated in the BIOS of the CPM80 from the given data by sector and track. The logic sector size of CP/M 2.2 is 128Byte, the physical sector size of ECB-RAMF 11 is 512 Byte. These data are converted in exactly the information that is pre-loaded into the address counter as the starting address. The counter done thereby completely the byte addressing within a sector, the sector address and the track addressing. The following chart shows how the address in the address space of 4 Mbytes of SRAM composed resulting from the calculated data passed by the BIOS. This figure applies to the assignment of 128Byte/Sektor.


adress-calculation of ECB-RAMF R11

Byte-Counter Byte Address (0…511 in IC12)

SecTrk-low Sector Track Address low (IC10)

SecTrk-high Sector Track Address high (IC11)

Electronic of ECB-RAMF

Function of address counter (Byte-in-Sector-Counter) and I/O-Access-Logic

Address counter

In contrast to the sector number, the Counter can not be set directly.He can only be reset to “0” by write access to one of the sector registers (on Sector-Track Address Register-Low (IC10A) or Sector-Track-Address-Register-High (IC11A)), and reading / writing to the data register (Data-Read Data Write (IC9A)) by increasing of 1.This allows a continuous stream length of one physical sector (512 bytes) of data register to read the.This mechanism allows only the high transmission speed of the assembly. The “Byte-in-Sector” counter consists of one 74HCT-IC (74HCT4040) and thus covers the 9-Bit-address space of the ECB-RAMF of 4 Mbytes. |

the clock and control signals (timing) of the 74HCT4040

Waveforms showing the clock (/CP) to output (Q)

I/O-Timing of the Z80-CPU, Controlsignals in ECB-RAMF

Figure above illustrates an I/O read or I/O write operation of the Z80-CPU. During I/O operations a single wait state is automatically inserted. The reason is that during I/O operations, the time from when the IORQ signal goes active until the CPU must sample the WAIT line is very short. Without this extra state, sufficient time does not exist for an I/O port to decode its address and activate the WAIT line if a wait is required. Also, without this wait state, it is difficult to design MOS I/O devices that can operate at full CPU speed. During this wait state time, the WAIT request signal is sampled. During a read I/O operation, the /RD line is used to enable the addressed port onto the data bus just as in the case of a memory read. For I/O write operations, the /WR line is used as a clock to the I/O port. This timing is necessary to understand why IC10A and IC11A are edge triggered and how the I/O-interface controls the Byte-sector address counter. The registers IC11A and IC12A are latched with a low-high transition. The address decoding logic (IC17A, IC14A, IC13A and IC18A+B) is connected to the address bus lines AB2-AB7, to /IORQ, /WR and to /M1. If the address at S1 is identical to the address in the software/firmware the outputs Y1 or Y2 are going to LOW if all signals are active. At the end of /WR those outputs are going to HIGH and the data on the databus is latched into IC10A (RAMF_AL) or IC11A (RAMF_AH). With the help of IC19D is the RESCNT-signal generated. This RES-signal must be static HIGH to reset IC12A. This state is active at the beginning of each access cycle to IC10A or IC11A. At the end the latches are filled and the RES-signal of IC12A is inactive. The latches IC10A and IC11A are only accessable when /WR is active. This circuit is good for a correct I/O-Timing and if the user takes SRAM with 55/70ns access time. If in the software is an I/O-Access to RAMF_DAT the output Y0 comes to LOW (active) state. This signal is connected to the /G-Input of IC9A and to IC16E. IC16E inverts this signal. This is necessary because IC12A is counting with a HIGH-LOW-edge on Input P1. This occurs at the end of each R/W-cycle to IC9A (RAMF_DAT). This is correct so that an Byte-address change occurs AFTER each R/W-access to the memory.

The battery-backup of the SRAM

The battery backup of the contents of the memory is an important basic property ECB-RAMF a RAM floppy. Through the use of CMOS SRAM can easily implement this basic property. D1 and D2 are the “two way” power-supply for all 8 CMOS memory available and the CS-decoder IC14A and turn it around between the supply voltage VCC and B_VCMOS. The maximum value of current consumption for CMOS SRAM and some elements in the decoding logic (RN2, R4, R5, C15-C22) is 800mA. The memory IC pull in a typical operating current of 10…50mA in the access mode with pulsed / CS signals. This depends on the different types of CMOS-RAMs. Type Current in operating mode current in sleep mode CS18LV40965 55mA 2,5 … 20μA CHiPLUS AS6C4008 30…60mA 4 … 50μA Alliance Memory LY625128 40…60mA 5 … 25μA Lyontec Inc HY628400A 10mA 30 …100μA Hynix (SMT) K6T4008C1B 80mA max. 50 … 100μA SAMSUNG HM628512A 45…70mA max. 50 … 100μA Hitachi Was the current in the buffer operation with fully equipped with the building blocks depends on the used type of SRAM. Please be careful: one PCB may use only for SRAM-power more then 600mA. This was the reason that I couldn´t implement an power management IC with power switching for SRAM. The most IC deliver not more then 400mA.


In standard mode, the supply voltage VCC is active. The 8 CMOS-RAM are connected via D1 to VCC. The supply voltage VCC is reduced by the voltage UD1 from 5V to 4,7V as VCMOS. D1 must be a Shottky-type with current of 1A (1N5817). IC15 works as voltage supervisor. The TLC77xx family of micropower supply voltage supervisors provide reset control, primarily in microcomputer and microprocessor systems. During power-on, RESET is asserted when VDD reaches 1 V. After minimum VDD (≥2 V) is established, the circuit monitors SENSE voltage and keeps the reset outputs active as long as SENSE voltage (VI(SENSE)) remains below the threshold voltage. An internal timer delays return of the output to the inactive state to ensure proper system reset. The delay time, td, is determined by an external capacitor C23: td = 2.1 × 104 × CT Where CT is in farads td is in seconds The calculation gives an value of C23 of 100nF. The threshold voltage of the used TLC7705IP is 4,55V.


A special task has IC15. I the case of “power down” the voltage VCC is switched off and VCMOS is now generated via D2 from B_VCMOS. The moment of switching is critical for CMOS-RAMS. The can lost information and there could be start unsolved write-cycles to the memory chips. In addition to the power-on-reset and undervoltage-supervisor function, the TLC77xx adds power-down control-support for static RAM. The voltage monitor contains additional logic intended for control of static memories with battery backup during power failure. The memory circuit is automatically disabled during a power loss because in this the signal /RESET is going LOW. (In this application the TLC77xx power has to be supplied by the battery.) The TI-solution to solve this problem is shown in picture 4.6. Please be careful, in picture 4.6 is an CPU (TMS70C20). In the ECB-RAMF this IC is the RAM-Access-Decoder IC14A and the Input G1. G1 of IC14A must be “HIGH” to to give access to the RAM-IC. If the signal /IC15-R on G1 is going to LOW, the access to RAM-IC is denied. fig_47.jpg

Solution from Texas Instruments: Data Retention Power Down using Static CMOS RAMs

D1 and D2 must be 1A shottky diodes (1N5817).

Status displays of the ECB-RAMF

The status display is realized by 3 LEDs. These three LEDs indicate as follows:

LED1A (red) display “Option Bit” LED1B (yellow) display “VDD available / not available” LED1C (green) activity indicator read-write access to data ECB-RAMF The activity indicator (LED1) indicates access to the data register with an LED. It is pure gimmick and has no effect on the function of the module. Simply put, they would leave easily. But, as the user wants to be seen whether and how the requests already running on the storage medium.
The operation is very simple. The DIR signal of the data register (I/O decoder IC13 output 11, OR addition over /RD) is connected to the INT0 pin of ATtiny13 connected. This signal changes from high to low level (falling edge) triggers an interrupt in the ATtiny13, initialize a timer which switches on and activates the LED as well. If the timer expires, then it will turn the LED off. Technically, the circuit is simpler than a retriggerable one-shot, and also takes up less space on the board.
The fuse bits of the ATtiny13 must not be programmed. The program is configured for its delivery.


The bus interface of the ECB-RAMF is performed by the ECB-bus standard from Kontron. The ECB system is an 8-bit parallel bus, which is originally designed for the Z80 microprocessor family. Since the ECB-bus is not in accordance with DIN / IEC / IEEE / … is specified, various ECB-bus pin assignments have been established in the market. The pin assignment of the ECB-RAMF corresponds to Kontron-ECB-assignment.

Peculiarities and exceptions:

* The screen surface is at ABC32 GND (GND)

* 2 power lines, Row ABC1 (electricity supply ), number ABC32 (GND)

* The backup battery is not located on the ECB-RAMF, only over the contact of the ECB-Bus A25

* Designed as ECB-bus option B

* The pins 11C (IEI), 16C (IEO) on the module are connected directly on the board

* The pins 12A (BAI) and 17A (BAO) are connected directly on the board

* Resetting of the address counter is optionally reversible:

over B_/RESET on C31 or B_/PWCLR on C26. This change was intended to operate as it were by CPU with pure Kontron standard or CPU with N8VEM standard with the RAM-floppy module. Switching is done via S3-1 (B_/PWCLR) or S3-2 (B_/RESET).

That´s why is the law: B_/RESET ^ B_/PWCLR

There is only one source may be selected The card format is ECB-PCB (100 mm × 160 mm, 3U) and two-row or three-row connector conform to DIN 41612. The data bus is bi-directionally with the driver IC IC9 (74LS245, maybe also 74LS645) is coupled. The data bus address bus and control bus are guided over the driver IC20, IC21 and IC22. These ICs are designed with a Schmitt trigger inputs and decouple the ECB-RAMF from the ECB-Bus (avoid excessive bus loads → Fan Out and Fan-in = 1)
A special feature of the IC22 Represents This driver consists of two halves, each with 4 bits. This 4-bit with Schmitt-trigger input to decouple the control signal /RD, /WR, /IORQ and /M1 from the bus can be used (IC22A). The other 4 bits (IC22B) are used to signal status of the ECB-RAMF to switch to the bus. These are programmatic evaluation.
The IC17A (74LS688) serves in conjunction with S1 and RN1 as I/O address decoder of the assembly. The 8 /CS signals for the SRAM-IC are formed from the ECB-RAMF-activation (IC17), the /CS decoder (IC15) and the CMOS buffer battery voltage monitoring (D1, D2 and IC15). The address latches (IC10A and IC11A) -are addressed and loaded by the ECB-RAMF-activation (IC17A) and the I/O-address decoder (IC13A).

Assembly instructions


Dealing with IC

CMOS devices are highly sensitive to static electricity! Keep your transport or CMOS chips on only conductive foam! All pins must be shorted.
Make sure that you connect to a grounding system before working with these modules. ESD is appropriate article in the trade. All IC with blocking capacitors are 100nF X7R-5 (0,1 uF Tantal is also ok, please be careful with polarization) provided. This is absolutely important. Otherwise there is an reduction of the functionality of the module due to EMC influence.

Assignment of connectors, jumpers and switches

Down the text the assembly and the switch position of the ECB Standard-I/O-address ECB-RAMF R11 is shown. Basically, the I/O-address range will be adjusted to your taste. Keep in mind that this is reflected in the test program and drivers.

A closed switch means a 0-bit in the address specification. Here are some simple examples with board-start-address 0A0H #1 and 0A4H #2.


This definition is only for example. The real combination depends on Your life system.

For a 4Mbyte singe-PCB system You need the addresses as follows:

RAMF_BAS EQU 0A0H ; Base address of RAMF

RAMF_DAT EQU RAMF_BAS ; Data In/Out only to SRAM R/W

RAMF_AL EQU RAMF_BAS+1 ; Address low for RAMF Memory Cell W

RAMF_AH EQU RAMF_BAS+2 ; Address high for RAMF Memory Cell W

RAMF_ST EQU RAMF_BAS+3 ; Statusport R/O

For a 2 * 4MByte double-PCB system You need the addresses as follows:

RAMF_BAS1 EQU 0A0H ; Base address of RAMF#1

RAMF_DAT1 EQU RAMF_BAS1 ; Data In/Out only to SRAM R/W

RAMF_AL1 EQU RAMF_BAS1+1 ; Address low for RAMF Memory Cell W

RAMF_AH1 EQU RAMF_BAS1+2 ; Address high for RAMF Memory Cell W

RAMF_ST1 EQU RAMF_BAS1+3 ; Statusport R/O

RAMF_BAS2 EQU 0A4H ; Base address of RAMF#2

RAMF_DAT2 EQU RAMF_BAS2 ; Data In/Out only to SRAM R/W

RAMF_AL2 EQU RAMF_BAS2+1 ; Address low for RAMF Memory Cell W

RAMF_AH2 EQU RAMF_BAS2+2 ; Address high for RAMF Memory Cell W

RAMF_ST2 EQU RAMF_BAS2+3 ; Statusport R/O



Since RomWBW 2.5.2. we find as first step 2 RAM-Floppies with an size of 4MB on each PCB.

Address assignment of ECB-RAMF-R11

AD7 AD6 AD5 AD4 AD3 AD2 AD1 AD0 /RD /WR comment
X X X X X X 0 0 1 1 not active
X X X X X X 0 0 1-0-1 1 Read Data with CNT
X X X X X X 0 0 1-0-1 1 Write Data with CNT
X X X X X X 0 1 1 1-0-1 Write Address Low
X X X X X X 1 0 1 1-0-1 Write Address High
X X X X X X 1 1 1-0-1 1 Read Status

Write to Address Low or Address resets the Counter IC12A.

Jumper S4:

S4/1 close = AB2 = 0

S4/2 close = AB3 = 0

S4/3 close = AB4 = 0

S4/4 open = AB5 = 1

S4/5 close = AB6 = 0

S4/6 open = AB7 = 1

Base-address table


0 0 0 0 00H free

0 0 0 1 10H preferred for ECB Zilog Peripherals

0 0 1 0 20H reserved for ECB Disk IO

0 0 1 1 30H reserved for ECB Disk IO

0 1 0 0 40H 40H - 47H preferred for PropIO

0 1 0 1 50H 50H - 58H preferred for ECB SCG board

0 1 1 0 60H reserved for N8VEM SBC V2

0 1 1 1 70H reserved for N8VEM SBC V2

1 0 0 0 80H preferred for uPD7220 board

1 0 0 1 90H preferred for EF9366 board VDU

1 0 1 0 0 0 A0H preferred for ECB-RAMF R11 #1

1 0 1 1 0 1 A4H preferred for ECB-RAMF R11 #2

1 1 0 0 C0H prefered for ECB-ModPrn R0.2 #1 and

#2 (if used in system)

1 1 0 1 D0H prefered for ECB-4PIO (if used in

system) or preferred for EF9366 board Hardware scroll

1 1 1 0 E0H preferred for ECB ColorVDU board

1 1 1 1 F0H free

Jumper S3:

S3/1 reset the counter with signal B_/PWCLR

S3/2 reset the counter with signal B_/RESET

S3/3 /Option_Bit = 0

Switch S2:

If the switch S2 is closed (switch down), the write protection is active. This prevents over IC18C that the CMOS memory can be described with a write access.
The switch S2 generates the signal “PROT”. About the status of port RAFECB_BAS +3, the following signals from the circuit of ECB-RAMF be imported and evaluated in the program


DB3 activity


Connector P1:

Row a (8 Bit)




a1 +

5V +

5 volts dc



Data line bit 5



Data line bit 6



Data line bit 3



Data line bit 4



Address 2



Address 4



Address 5



Address 6



CPU wait



bus request









address 14




first cycle









in/out request



refresh cycle



address 13



address 9



bus acknowledge



signal ground

Row b is not used!

Row c (8 Bit)






+5 volts DC



Data line bit 0



Data line bit 7



Data line bit 2



Address 0



Address 3



Address 1



Address 8



Address 7




interrupt enable in





Data line bit 1




interrupt enable out



address 11



address 10




not maskable interrupt



normal interrupt



write cycle




read cycle



cpu stopped



CPU Reset (as output to ECB)



address 12



address 15



System Clock from CPU



memory request



cpu reset (as input from ECB)



signal ground

The ATTINY13-20

IC23 is an ATTINY13-20. It´s much more easier to use an Mikrocontroller in the activity function as an retriggerable monoflop with external capacities and resistors. To programm this chip You may find the HEX-File in the WiKi.

As programming technology You may use PONY-Prog. Here is the link:

For our German and European friends … You may use a simple PCB from POLLIN and the software PONYPROG. Here is the link to the POLLIN-PCB:

boards/ecb/ramfloppy/start.txt · Last modified: 2015/11/01 03:02 by wkabatzke
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