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ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8145] Sun, 20 December 2020 17:08 Go to next message
plasmo is currently offline  plasmo
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ZZRCC (Z280+RAM+CPLD+CF disk) is a simpler replacement for ZZ80CF. The component counts is now 3 ICs plus an oscillator instead of ZZ80CF's 6 IC, 2 oscillators, and a battery. ZZRCC also fixed the problem with asynchronous baud clock which intermittently injects spurious character in output. ZZRCC also has an I2C connector specifically for 128x64 OLED display.

The design approach of ZZRCC is quite different than ZZ80CF. Like ZZ80CF, the Z280 processor is operating in the 8-bit Z80-compatible mode. It also uses the same Z280 serial bootstrap function to load initial software into memory, but instead of storing the monitor in battery-backed RAM, it stores the monitor in the CF disk. During normal booting, a small ROM in CPLD loads the monitor from designated location in CF disk into RAM and execute. This approach eliminates the battery and the battery supervisor. I'm also pleased to squeeze all ZZRCC functions in the smallest & cheapest Altera CPLD, EPM7032SLC44. All in all, I'm quite pleased with this design.

ZZRCC homepage is here: https://www.retrobrewcomputers.org/doku.php?id=builderpages: plasmo:zzrcc

Bill
/forum/index.php?t=getfile&id=1945&private=0
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8146 is a reply to message #8145] Sun, 20 December 2020 17:24 Go to previous messageGo to next message
plasmo is currently offline  plasmo
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This is ZZRCC driving 128x64 OLED display over I2C bus. The I2C bus is a simple bit-bang interface.
Bill

/forum/index.php?t=getfile&id=1946&private=0
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8153 is a reply to message #8146] Wed, 23 December 2020 01:38 Go to previous messageGo to next message
b1ackmai1er is currently offline  b1ackmai1er
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Very Very nice.
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8154 is a reply to message #8153] Wed, 23 December 2020 15:27 Go to previous messageGo to next message
plasmo is currently offline  plasmo
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Thank you.

I also ported Conway's Life playing Gosper's Glider gun. The small 128x64 screen is rather limiting. I like to try the 320x240 QVGA screen which is surprisingly inexpensive now.

I have successfully built up 4 ZZRCC. After Christmas break, I plan to offer the remaining 6 boards either as $30 kits or $40 assembled/tested boards plus $5 shipping in USA or $15 International. If I have leftover after few weeks, I'll auction them off on eBay starting from $1.
Bill

[Updated on: Wed, 23 December 2020 15:28]

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Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8177 is a reply to message #8154] Sat, 09 January 2021 17:40 Go to previous messageGo to next message
quarterturn is currently offline  quarterturn
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That's very tidy! Is there a way to set the clock divider so it could have the option of running at 3.579545 MHz while still having a normal serial baudrate? I'd like to play around with old Coleco or MSX game stuff, which used a Z80 at that frequency. I've got a Z180 setup which has to run at a very nonstandard 23040 baud while running at 3.686 MHz (close enough to 3.579545). I'd be interested in one if Coleco/MSX speed isn't too much work.

BTW I saw you finished your ZZ80MB EEPROM programmer code, so I got that set up on mine. Very nice to be able to bootstrap from EEPROM now.

I hope you'll come back to the 68030 stuff. I'd love to see the CB030 evolve into something supporting ethernet and storage. I haven't touched mine since I got the linux demo running on it, sadly.
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8178 is a reply to message #8177] Sat, 09 January 2021 22:16 Go to previous messageGo to next message
wsm is currently offline  wsm
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Quote:
... I've got a Z180 setup which has to run at a very nonstandard 23040 baud while running at 3.686 MHz ...
I agree that 23040 is a very non-standard baud rate. However, it should be quite straightforward to swap a Z80180 with a Z8S180 which has an additional baud rate generator (BRG). It will require a change to the ASCI initialization but the BRG will allow standard baud rates up to 38400 with a PHI of 3.686 MHz.
i.e. TC=1=38400, TC=4=19200, TC=10=9600, etc.

If you're using the CSI/O the Z8S180 may cause an issue with the timing and/or residual value of the last bit sent.
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8180 is a reply to message #8177] Sun, 10 January 2021 06:18 Go to previous messageGo to next message
plasmo is currently offline  plasmo
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quarterturn wrote on Sat, 09 January 2021 18:40
That's very tidy! Is there a way to set the clock divider so it could have the option of running at 3.579545 MHz while still having a normal serial baudrate? I'd like to play around with old Coleco or MSX game stuff, which used a Z80 at that frequency. I've got a Z180 setup which has to run at a very nonstandard 23040 baud while running at 3.686 MHz (close enough to 3.579545). I'd be interested in one if Coleco/MSX speed isn't too much work.

BTW I saw you finished your ZZ80MB EEPROM programmer code, so I got that set up on mine. Very nice to be able to bootstrap from EEPROM now.

I hope you'll come back to the 68030 stuff. I'd love to see the CB030 evolve into something supporting ethernet and storage. I haven't touched mine since I got the linux demo running on it, sadly.
If 3.68MHz works for you, I can easily change the clock divider to /4 so your serial port can run at the standard 57600. Because Z280 CPU clock is 1/2 the input oscillator, the oscillator you'll need is actually 7.3728MHz. The much bigger question is whether Z280 is compatible with MSX. If you don't use Z280's internal functions like UART, timer, DMA, MMU, OK, it is more likely to be compatible, but then it is no better than a Z80.

I'm out fooling around with 6502. I recently added two 6502 homepages on my builder page:
https://www.retrobrewcomputers.org/doku.php?id=builderpages: plasmo:protor5:proto65:proto65r02
https://www.retrobrewcomputers.org/doku.php?id=builderpages: plasmo:crc65

I have plan to add video and keyboard capabilities to all my 68K, Z280, and Z80 products. That was my goal for this winter, but as you can see, I was distracted.
Bill
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8182 is a reply to message #8180] Mon, 11 January 2021 06:33 Go to previous messageGo to next message
lintweaker is currently offline  lintweaker
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plasmo wrote on Sun, 10 January 2021 15:18
The much bigger question is whether Z280 is compatible with MSX. If you don't use Z280's internal functions like UART, timer, DMA, MMU, OK, it is more likely to be compatible, but then it is no better than a Z80.
Indeed. I did a lot of experimenting trying to use the Z280 a the main cpu for MSX. I can be made to work but a that point the Z280 is slower then the regular Z80.
The Z280 cache cannot really be used as it interferes with the MSX slot mechanism and maybe some BIOS code (self modifying? WinkWink.
I played a lot with the clock and clock dividers, the MSX architecture quickly shows it limits.
Booting MSX1 is fairly easy, later models (2,2+) not so much.

[Updated on: Mon, 11 January 2021 06:34]

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Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8183 is a reply to message #8182] Mon, 11 January 2021 12:56 Go to previous messageGo to next message
lowen is currently offline  lowen
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So, this is the board I've really been waiting on. Like I originally said in my thread that morphed into the CPU280 revival thread, I have always wanted a Z280 speedup board for a TRS-80 model 4. Well, with a few modifications, ZZRCC is that board. The RC2014 bus, with a little bit of work, can interface back to a Z80 socket easily enough. I've booted a ZZRCC here, and now to design the modifications to make it drive a Z80 socket.

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Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8184 is a reply to message #8145] Mon, 11 January 2021 14:58 Go to previous messageGo to next message
hperaza is currently offline  hperaza
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Very nice design, indeed. Although I miss the RTC chip, needed for CP/M 3, MP/M, UZI280 and RSX280.
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8185 is a reply to message #8184] Mon, 11 January 2021 17:47 Go to previous messageGo to next message
plasmo is currently offline  plasmo
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hperaza wrote on Mon, 11 January 2021 15:58
Very nice design, indeed. Although I miss the RTC chip, needed for CP/M 3, MP/M, UZI280 and RSX280.
Interesting you should say that. Since ZZRCC does have an I2C interface, I'm just thinking about a small I2C board with RTC and stack-able 4-pin connector so the 128x64 OLED display can plug on top of it. The purpose is a clock where RTC provides the time base and 128x64 OLED the clock face. Will such a board serve your purpose, or do you also need an interrupt associated with it?
Bill
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8186 is a reply to message #8183] Mon, 11 January 2021 17:58 Go to previous messageGo to next message
plasmo is currently offline  plasmo
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lowen wrote on Mon, 11 January 2021 13:56
So, this is the board I've really been waiting on. Like I originally said in my thread that morphed into the CPU280 revival thread, I have always wanted a Z280 speedup board for a TRS-80 model 4. Well, with a few modifications, ZZRCC is that board. The RC2014 bus, with a little bit of work, can interface back to a Z80 socket easily enough. I've booted a ZZRCC here, and now to design the modifications to make it drive a Z80 socket.
You may have tight space to work with, if so I can easily redesign the board to suit your application. Heck, if you've been wanting to do that all these years, I'm sure there are many other TRS-80 fans on VCFED that'll also be interested. So let me know what you need, I'm happy to help.
Bill
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8187 is a reply to message #8184] Mon, 11 January 2021 20:50 Go to previous messageGo to next message
dittman is currently offline  dittman
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hperaza wrote on Mon, 11 January 2021 14:58
Very nice design, indeed. Although I miss the RTC chip, needed for CP/M 3, MP/M, UZI280 and RSX280.
While it's nice to have, CP/M Plus doesn't have to have an RTC chip.
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8188 is a reply to message #8185] Tue, 12 January 2021 09:46 Go to previous messageGo to next message
hperaza is currently offline  hperaza
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Quote:
Interesting you should say that. Since ZZRCC does have an I2C interface, I'm just thinking about a small I2C board with RTC and stack-able 4-pin connector so the 128x64 OLED display can plug on top of it. The purpose is a clock where RTC provides the time base and 128x64 OLED the clock face. Will such a board serve your purpose, or do you also need an interrupt associated with it?
It will do, although I'd prefer the RTC chip on board. But I can see that there is almost no space remaining. BTW, I noticed that your ZZ80MB rev 3 (another design I like) does not have an RTC either? Rev 1 had it.
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8189 is a reply to message #8187] Tue, 12 January 2021 10:07 Go to previous messageGo to next message
hperaza is currently offline  hperaza
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dittman wrote on Mon, 11 January 2021 20:50
While it's nice to have, CP/M Plus doesn't have to have an RTC chip.
True, but if can have a feature you will want to have it Smile. Without an RTC CP/M 3 will not have timestamps, and utilities like 'make' will not work. Yes, you could still maintain the TOD using timer interrupts, but is annoying having to enter the time and date every time you (re)boot the system. But the Z280 is a bit overkill for CP/M 3 anyway; it really shines in multitasking, and with multitasking OSes an RTC is normally a must.
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8190 is a reply to message #8189] Tue, 12 January 2021 12:17 Go to previous messageGo to next message
dittman is currently offline  dittman
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hperaza wrote on Tue, 12 January 2021 10:07
dittman wrote on Mon, 11 January 2021 20:50
While it's nice to have, CP/M Plus doesn't have to have an RTC chip.
True, but if can have a feature you will want to have it Smile. Without an RTC CP/M 3 will not have timestamps, and utilities like 'make' will not work. Yes, you could still maintain the TOD using timer interrupts, but is annoying having to enter the time and date every time you (re)boot the system. But the Z280 is a bit overkill for CP/M 3 anyway; it really shines in multitasking, and with multitasking OSes an RTC is normally a must.
Yes, entering the date and time on reboot is annoying. I used timer interrupts in my Model 4 CP/M Plus BIOS. It worked. Had an external RTC like the Newclock/80 been cheaper I'd have bought one.
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8194 is a reply to message #8186] Wed, 13 January 2021 07:52 Go to previous messageGo to next message
lowen is currently offline  lowen
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plasmo wrote on Mon, 11 January 2021 20:58

You may have tight space to work with, if so I can easily redesign the board to suit your application. Heck, if you've been wanting to do that all these years, I'm sure there are many other TRS-80 fans on VCFED that'll also be interested. So let me know what you need, I'm happy to help.
Bill
Wow. Let me think about this; I want to be very careful to not overcommit here....I've done that before, and caused some problems this past year.


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Bughlt: Sckmud
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Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8195 is a reply to message #8194] Wed, 13 January 2021 08:41 Go to previous messageGo to next message
dittman is currently offline  dittman
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lowen wrote on Wed, 13 January 2021 07:52
plasmo wrote on Mon, 11 January 2021 20:58

You may have tight space to work with, if so I can easily redesign the board to suit your application. Heck, if you've been wanting to do that all these years, I'm sure there are many other TRS-80 fans on VCFED that'll also be interested. So let me know what you need, I'm happy to help.
Bill
Wow. Let me think about this; I want to be very careful to not overcommit here....I've done that before, and caused some problems this past year.
I'd definitely be interested.
Re: ZZRCC, Z280+RAM+CPLD+CFdisk, replacing ZZ80CF. [message #8208 is a reply to message #8180] Tue, 19 January 2021 13:47 Go to previous message
quarterturn is currently offline  quarterturn
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I'll probably build a standard Z80 board combo just to be sure the games work. Of course the sensible thing would have been to simply use an emulator and left it at that, but NO I am doing it the hard way! Razz

[Updated on: Tue, 19 January 2021 13:48]

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