[vcf-midatlantic] Working Tandy 1000 or 2000

Kelly Leavitt kelly at catcorner.org
Thu Aug 30 15:20:35 EDT 2018

OK, I'll see if I have the TX. Based on the (known unreliable) technical reference manual, the 1000TX uses the NCR 8496.

From: Jonathan Gevaryahu <jgevaryahu at gmail.com>
Sent: Thursday, August 30, 2018 2:21 PM
To: Kelly Leavitt; Dean Notarnicola; vcf-midatlantic
Subject: Re: [vcf-midatlantic] Working Tandy 1000 or 2000

The 1000TX I've heard (but am not sure) uses an NCR8496, but again, just a rumor.

On 8/30/2018 10:23 AM, Kelly Leavitt wrote:

Just confirmed, my 1000SX has the SN76496 TI chip. I'll have to look at the others in this family.

From: Dean Notarnicola <dnotarnicola at gmail.com><mailto:dnotarnicola at gmail.com>
Sent: Wednesday, August 29, 2018 11:48 PM
To: vcf-midatlantic
Cc: Jonathan Gevaryahu; Kelly Leavitt
Subject: Re: [vcf-midatlantic] Working Tandy 1000 or 2000

I just picked up an SX.  I'll check it in the morning

On Wed, Aug 29, 2018 at 11:13 PM Jonathan Gevaryahu via vcf-midatlantic <vcf-midatlantic at lists.vcfed.org<mailto:vcf-midatlantic at lists.vcfed.org>> wrote:
The problem is I've found that the parts lists in some of the Tandy
manuals is incorrect.

On 8/29/2018 10:11 PM, Kelly Leavitt wrote:
> 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<mailto: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>>
>> <mailto: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> <mailto: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>>
>>>> <mailto: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>>
>>>> <mailto: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>
>>>> <mailto: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>

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