[vcf-midatlantic] Working Tandy 1000 or 2000

Kelly Leavitt kelly at catcorner.org
Wed Aug 29 22:11:01 EDT 2018


OK, sorry I got that backward. I have an SX apart on the bench for some testing. I cannot find any chip with either part number. It is either hiding under a Tandy house number or part of the 2 big (for the time) ASICs. I'm pulling up the technical reference manual now.


OK, according to the parts list on P51, U37A is an SN76496 Tone Generator. That agrees with page 7 of the schematic.


I've attached screen grabs of these if they don't get stripped.


You can find the tech ref for the 1000sx at ftp://ftp.mindcandydvd.com/pub/drivers/Tandy/Tandy_1000SX_Technical_Reference_Manual.pdf


I'll verify the part number of IC U37A tomorrow.


________________________________
From: Jonathan Gevaryahu <jgevaryahu at gmail.com>
Sent: Wednesday, August 29, 2018 9:18 PM
To: Kelly Leavitt; vcf-midatlantic
Subject: Re: [vcf-midatlantic] Working Tandy 1000 or 2000

The TI chip is fairly well understood; the original Tandy 1000/1000HD, and the slightly enhanced 1000A used the 'real' TI chip, SN76496, for certain.
Its possible that the EX (and maybe HX?) also used it, but unclear.

The SX and TX (and maybe the HX?) SUPPOSEDLY used the weird NCR8496 chip, which is what I need tested. (assuming wikipedia is correct, which it actually isn't regarding the SN76496 on the Tandy 1000/1000A...)
The SL2, TL2, RLX, RSX use the PSSJ-3 ASIC, which would also be ok for testing, but ideally I'd like to run these tests on both the NCR8496 and the PSSJ-3.


On 8/29/2018 8:36 AM, Kelly Leavitt wrote:

I have manyof the 1000 series computers (hx, ex, sx, sl, sl2, tl, etc). Do you know which used the wonky TI chip? I can always start opening them up.


________________________________
From: Jonathan Gevaryahu <jgevaryahu at gmail.com><mailto:jgevaryahu at gmail.com>
Sent: Wednesday, August 29, 2018 12:55 AM
To: Kelly Leavitt; vcf-midatlantic
Subject: Re: [vcf-midatlantic] Working Tandy 1000 or 2000

Another thing: I need to test against a tandy 1000-series with an NCR8496 or PSSJ-1 asic in it, i.e. not the original tandy 1000/1000a/1000hd, since they actually use a real TI SN76496 PSG which actually behaves differently! (that's the whole reason I need to do these tests, the behavior isn't consistent!)


On 8/29/2018 12:53 AM, Jonathan Gevaryahu wrote:
Indeed, I was thinking of the 1000 series, not the 2000.
I'm trying to figure the best way to run the tests from basic, i might need to mess around with dosbox to get the program written, since MAME has keyboard issues with the tandy machines (which I'd also love to fix...)



On 8/28/2018 8:45 PM, Kelly Leavitt wrote:

The 2000 and the 1000 were remarkably different beasts. The 2000 had a basic speaker that did beeps. There was a rumored TV board but I have never seen one in the wild. Fun tidbit, the 2000 loaded BIOS from floppy (a 720k 5.25 inch floppy). The built in ROM was a simple boot loader.


The 1000 was mostly compatible with the XT/jr with some added sound and graphics capabilities.


I have working models of the 1000 hear that I cant test with Tandy's Basica if you'd like. My 2000's are iffy so I can't make any promises. Send me the pokes you'd like to try.


Kelly

kelly at catcorner.org<mailto:kelly at catcorner.org>


________________________________
From: vcf-midatlantic <vcf-midatlantic-bounces at lists.vcfed.org><mailto:vcf-midatlantic-bounces at lists.vcfed.org> on behalf of Jonathan Gevaryahu via vcf-midatlantic <vcf-midatlantic at lists.vcfed.org><mailto:vcf-midatlantic at lists.vcfed.org>
Sent: Sunday, August 26, 2018 5:16 AM
To: vcf-midatlantic at lists.vcfed.org<mailto:vcf-midatlantic at lists.vcfed.org>
Cc: Jonathan Gevaryahu
Subject: [vcf-midatlantic] Working Tandy 1000 or 2000

Does VCF have a working Tandy 1000 or 2000 on display or in the warehouse?

I need someone with access to a working Tandy 1000/2000 to do some
poking from basic of the sound chip, since there's an issue I'm running
into with a possible incompatibility of the Tandy 1000/2000 NCR8496 PSG
(sound chip) and the more common SN76489/SN76496 PSG which the
colecovision etc used.

--
Jonathan Gevaryahu
jgevaryahu at gmail.com<mailto:jgevaryahu at gmail.com>
jgevaryahu at hotmail.com<mailto:jgevaryahu at hotmail.com>



--
Jonathan Gevaryahu
jgevaryahu at gmail.com<mailto:jgevaryahu at gmail.com>
jgevaryahu at hotmail.com<mailto:jgevaryahu at hotmail.com>


--
Jonathan Gevaryahu
jgevaryahu at gmail.com<mailto:jgevaryahu at gmail.com>
jgevaryahu at hotmail.com<mailto:jgevaryahu at hotmail.com>


--
Jonathan Gevaryahu
jgevaryahu at gmail.com<mailto:jgevaryahu at gmail.com>
jgevaryahu at hotmail.com<mailto:jgevaryahu at hotmail.com>


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