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Re: 70x1 Memory Access Timing: Internal -versus- External Access [message #10663 is a reply to message #10660]

Fri, 05 April 2024 06:07

lynchaj
Messages: 1080
Registered: June 2016

Senior Member

Hi
Today I learned something about TMS7000 series that I did not know. Apparently, the TMS7000 allows for custom microcode and CPU instructions for application specific processing.

I wonder if Radio Shack used this capability in the CTS256? If they did, it is part of the mask of the CPU itself and an external EPROM will not be able to duplicate it.

https://www.cpushack.com/2015/05/20/ti-tms7000-the-scat-micr ocontroller/

It is entirely possible that my experiment of using the TMS7001 in microprocessor mode plus external EPROM to duplicate will not work. They may have been aware of this possibility and implemented a custom CPU instruction as a form of copy protection. I sure hope not but we are about to find out.

Thanks, Andrew Lynch

PS, this is the first I've I heard of something like it on 8-bit CPUs. I know modern processors can get microcode "patches" to update them and at least modify existing CPU instructions. Not so much add entirely new ones but I suppose that is possible too. Mainframes have been able to do this for quite a while but I can't imagine adding new instructions to a Z80 or 6502 as typical 8-bit microprocessor. Wow! The TMS7000 really *is* different that the rest.

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[Message index]

		General Instrument CTS256A-AL2 vs. Microchip CTS256AL2 By: lynchaj on Fri, 28 April 2023 03:28
		Re: General Instruments CTS256A-AL2 vs. Microchip CTS256AL2 By: jayindallas on Fri, 28 April 2023 13:10
		Re: General Instruments CTS256A-AL2 vs. Microchip CTS256AL2 By: scruss on Sat, 06 May 2023 16:46
		Re: General Instruments CTS256A-AL2 vs. Microchip CTS256AL2 By: lynchaj on Sat, 06 May 2023 18:13
		Re: github project may have extracted the CTS256A-AL2 code By: jayindallas on Sat, 06 May 2023 20:45
		Re: General Instruments CTS256A-AL2 vs. Microchip CTS256AL2 By: gkaufman on Sun, 07 May 2023 07:11
		Re: Programming the Naval algorithm as a CTSx for PIC/TMS7000 or otherwise By: jayindallas on Sun, 07 May 2023 16:26
		Re: General Instruments CTS256A-AL2 vs. Microchip CTS256AL2 By: lynchaj on Mon, 08 May 2023 04:04
		Re: Is the PIC/TMS7041 field programmable? By: jayindallas on Mon, 08 May 2023 08:25
		Re: Is the PIC/TMS7041 field programmable? By: lynchaj on Mon, 08 May 2023 12:50
		Re: No source of new-old CTS256A-AL2 economical micro solutions By: jayindallas on Mon, 08 May 2023 16:37
		Re: No source of new-old CTS256A-AL2 economical micro solutions By: lynchaj on Tue, 09 May 2023 04:41
		Re: No source of new-old CTS256A-AL2 economical micro solutions By: scruss on Sun, 14 May 2023 09:40
		Re: No source of new-old CTS256A-AL2 economical micro solutions By: jayindallas on Sun, 14 May 2023 22:19
		Re: No source of new-old CTS256A-AL2 economical micro solutions By: scruss on Wed, 17 May 2023 07:11
		Re: No source of new-old CTS256A-AL2 economical micro solutions By: jayindallas on Wed, 17 May 2023 11:03
		Emulating a TMS/PIC7000 (CTS256A-AL2) in a new MCU... By: jayindallas on Sat, 20 May 2023 09:12
		CHAPTER 01 :: "Introduction to Hardware Emulation of the 7000 Series" By: jayindallas on Sun, 21 May 2023 11:08
		Re: General Instruments CTS256A-AL2 vs. Microchip CTS256AL2 By: lynchaj on Mon, 25 March 2024 11:23
		Re: General Instruments CTS256A-AL2 vs. Microchip CTS256AL2 By: lynchaj on Wed, 27 March 2024 19:11
		Re: General Instruments CTS256A-AL2 vs. Microchip CTS256AL2 By: lynchaj on Sun, 31 March 2024 08:46
		7000 Series Unobtainium may be OBTAINium? By: jayindallas on Sun, 31 March 2024 11:50
		Re: General Instruments CTS256A-AL2 vs. Microchip CTS256AL2 By: lynchaj on Sun, 31 March 2024 17:38
		Tables of Various 7000 Series Device Features/Specifications By: jayindallas on Sun, 31 March 2024 19:41
		Re: TMS7000 Series Devices (Manual section 2.1) By: lynchaj on Mon, 01 April 2024 12:01
		Prototyping 7xxx Devices appear to support External Memory?! By: jayindallas on Mon, 01 April 2024 18:37
		Re: TMS7000 Series Devices (Manual section 2.1) By: lynchaj on Wed, 03 April 2024 03:57
		Re: TMS7000 Series Devices (Manual section 2.1) By: lynchaj on Thu, 04 April 2024 04:59
		CTS256 resurrection from old 70xx & SP-0256* too?! By: jayindallas on Thu, 04 April 2024 08:56
		Re: TMS7000 Series Devices (Manual section 2.1) By: lynchaj on Thu, 04 April 2024 10:00
		70x1 Memory Access Timing: Internal -versus- External Access By: jayindallas on Thu, 04 April 2024 11:03
		Re: 70x1 Memory Access Timing: Internal -versus- External Access By: lynchaj on Fri, 05 April 2024 06:07
		TMS7000 Series with Custom Micro-Coded Instructions By: jayindallas on Fri, 05 April 2024 21:14
		Re: TMS7000 Series with Custom Micro-Coded Instructions By: lynchaj on Sat, 06 April 2024 16:52
		Daisy 256 & the Speech Processor By: jayindallas on Sat, 06 April 2024 21:32
		Re: Daisy 256 & the Speech Processor By: lynchaj on Sun, 07 April 2024 07:08
		Reverse-Engineering the Speech Processor ROM By: jayindallas on Sun, 07 April 2024 11:24
		Re: Reverse-Engineering the Speech Processor ROM By: lynchaj on Sun, 07 April 2024 18:13
		Re: Reverse-Engineering the Speech Processor ROM By: lynchaj on Mon, 08 April 2024 03:46
		Re: Reverse-Engineering the Speech Processor ROM By: jayindallas on Mon, 08 April 2024 14:23
		Re: Reverse-Engineering the Speech Processor ROM By: lynchaj on Tue, 09 April 2024 04:22
		Re: Reverse-Engineering the Speech Processor ROM By: lynchaj on Tue, 09 April 2024 09:49
		Re: Reverse-Engineering the Speech Processor ROM By: lynchaj on Tue, 09 April 2024 10:50
		Re: Reverse-Engineering the Speech Processor ROM By: jayindallas on Wed, 10 April 2024 20:40
		Re: Reverse-Engineering the Speech Processor ROM By: lynchaj on Thu, 11 April 2024 09:56
		Re:TMS700x Memory Interface Mode Timing Spreadsheet UPDATE By: jayindallas on Fri, 12 April 2024 08:16
		Re: What TMS7000 Family Data Manual Version Am I Using? By: lynchaj on Fri, 12 April 2024 13:54
		Re: What TMS7000 Family Data Manual Version Am I Using? By: lynchaj on Fri, 19 April 2024 03:37
		DAISY256 works By: lynchaj on Mon, 22 April 2024 03:36
		Re: DAISY256 works By: lynchaj on Mon, 22 April 2024 12:57
		Re: DAISY256 works By: lynchaj on Mon, 22 April 2024 15:10
		Re: DAISY256 works By: lynchaj on Tue, 23 April 2024 03:54
		Re: DAISY256 works By: lynchaj on Tue, 23 April 2024 12:02
		Re: DAISY256 works By: jayindallas on Tue, 23 April 2024 12:31
		Re: DAISY256 works By: lynchaj on Sat, 27 April 2024 12:12
		Baud Rate Tables for 70x1, 70x2, 70Cx2 By: jayindallas on Sun, 28 April 2024 21:43
		Re: DAISY256 works By: lynchaj on Mon, 29 April 2024 04:16
		Re: DAISY256 works By: plasmo on Mon, 29 April 2024 05:52
		Re: DAISY256 works By: jayindallas on Mon, 29 April 2024 15:09
		Re: DAISY256 works By: plasmo on Mon, 29 April 2024 20:25
		Re: DAISY256 works By: lynchaj on Tue, 30 April 2024 04:44
		Re: DAISY256 works By: berzerkula on Mon, 06 May 2024 19:31
		Re: DAISY256 works By: lynchaj on Tue, 07 May 2024 04:50
		Re: DAISY256 works By: berzerkula on Tue, 14 May 2024 22:37
		Re: DAISY256 works By: lynchaj on Wed, 15 May 2024 03:38
		Re: DAISY256 works By: scruss on Wed, 24 July 2024 15:46
		Re: DAISY256 works By: berzerkula on Tue, 26 November 2024 17:17
		Re: DAISY256 works By: lynchaj on Sun, 16 June 2024 11:21
		Re: DAISY256 works By: berzerkula on Mon, 15 July 2024 23:57

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