Re: PET 2001 fix Part 3 - RAM/ROM board etc.

From: Philip Lord <random6000_at_mac.com>
Date: Sat, 14 May 2011 18:30:24 +0900
Message-id: <737C2F95-40EA-4D25-9AA9-5C5FF54F648B@mac.com>
Thank again,.

One quick question before trying what you suggest. How are the BASIC2 901465-1/2/3 and 901447-24 ROM images organized on the 2532 and 2716 EPROMs? 
Do 1, 2, and 3 go on the 2532's at H1,H2 and H4, and the 901447-24 goes on a 2716 at H3????
I'll give this a go tonight. Fingers crossed.

Maybe I'll move this thread over to VCF, I don't want to have my emails clogging up peoples lives. Thanks for all the replies.

Phil


On May 14, 2011, at 6:19 PM, MikeS wrote:

> Too bad H5 is dead; the other four can all be 2716s.
> 
> There's no easy way to use 2716s there and you can't easily replace one 2716
> with a 2532, but you can replace a pair ;-)
> 
> If you have three 2532s, program 4K images C000-CFFF, D000-DFFF and
> F000-FFFF into the 2532s and insert them in H1, 2 and 4 respectively, with a
> 2716 containing E000-E7FF in H3. Leave H5, 6 and 7 empty.
> 
> You could even upgrade to BASIC2 while you're at it with the 901465-1/2/3
> and 901447-24 ROM images.
> 
> If you look at the schematic you'll see that each pair of low and high ROM
> sockets are wired exactly the same; the low 2316 is selected when pin 18 is
> low and the high one when it's high, and a 2532 essentially combines them
> with high and low on pin 18 (A11) selecting the high and low 2K halves.
> 
> Maybe the VCF forum might have been a better place for this; don't know if
> anyone else is interested.
> 
> As always, take my advice at your own risk ;-)
> 
> Good luck; fingers crossed.
> 
> mike
> 
> 
> ----- Original Message ----- From: "Philip Lord" <random6000@mac.com>
> To: <cbm-hackers@musoftware.de>
> Sent: Saturday, May 14, 2011 4:12 AM
> Subject: Re: PET 2001 fix Part 3 - RAM/ROM board etc.
> 
> 
> Me again,
> I have built the adaptor to read the 2316 H5, H6 and H7 into my burner using
> the 2K resistor. It seemed to work fine.
> 
> Now I have a complete list of which ROMs work and which are dead (compared
> to the 901447 set from Zimmers):
> 
> H1- DEAD (00's)
> H2- ok
> H3- DEAD (FF's)
> H4- ok
> H5- DEAD (every alternate second back of 128k is 00's, every alternate first
> bank has code but doesn't match 901447-02 at all)
> H6- ok
> H7- ok (unfortunately one of the pins completely broke off due to corrosion
> and I had  built a make shift fix for it, super ugly but works for testing
> until I can get the Nicolas's RAM ROM card fixed)
> 
> So three dead ROMs and one damaged (that sucks). I can burn 2716's for H1
> and H3, but I'll probably need to build an adaptor for a 2716 at H5. Do I
> make the adaptor similar to the programmer adaptor you described, but
> connect pin 18 to GND instead of VCC?
> 
> I also forgot to answer you question about 2532's. I do have some 2532's
> (and some 2732's I think) and my burner can program them. Why is it possible
> to use these as H5, H6, and H7 replacements if the code is doubled? Is the
> 2532 pin 18 active high? Doing a little bit of googling seems to suggest so.
> I'll do some more research.
> 
> Cheers
> 
> Phil
> 
> 
> On May 14, 2011, at 4:21 AM, MikeS wrote:
> 
>> If you have a spare 24pin IC socket, bend out pin 18 to isolate it and put
>> it between the 2316 and your programmer socket, and you might be able to
>> read the H5 - H7 ROMs that way; if not, try connecting that 2K resistor
>> between the bent-out pin 18 and pin 24.
>> 
>> Pleasant dreams ;-)
>> 
>> m
>> 
>> ----- Original Message ----- From: "MikeS" <dm561@torfree.net>
>> To: <cbm-hackers@musoftware.de>
>> Sent: Friday, May 13, 2011 3:06 PM
>> Subject: Re: PET 2001 fix Part 3 - RAM/ROM board etc.
>> 
>> 
>>> The ROM numbers and locations look good, but I would expect H1 to H4 to
>>> all
>>> read OK. Why not try putting your respective 2716 equivalents into H1 and
>>> H3, leaving the originals in H2, 4, 5, 6 and 7.
>>> 
>>> BTW, can you program 2532s and do you have any?
>>> 
>>> m
>>> 
>>> *******************
>>> 
>>> ----- Original Message ----- From: "Philip Lord" <random6000@mac.com>
>>> To: <cbm-hackers@musoftware.de>
>>> Sent: Friday, May 13, 2011 2:39 PM
>>> Subject: Re: PET 2001 fix Part 3 - RAM/ROM board etc.
>>> 
>>> 
>>> Don't worry, I'm not insulted at all.
>>> 
>>> I believe I have the following ROM set (I'll double check in the
>>> morning):
>>> 
>>> Location  Part Number
>>> ------------------------------
>>> H1  901447-09
>>> H2  901447-03
>>> H3  901447-05
>>> H4  901447-06
>>> H5  901447-02
>>> H6  901447-04
>>> H7  901447-07
>>> 
>>> And I have followed the above convention for placement. 09, 03, 05, 06,
>>> 02,
>>> 04 and 07 in that order.
>>> 
>>> When I read the original ROMs in my burner I got the following:
>>> 
>>> H1 - full of 00's
>>> H2 - good
>>> H3 - full of FF's
>>> H4 - good
>>> H5 - full of FF's
>>> H6 - full of FF's
>>> H7 - full of FF's
>>> 
>>> so is it possible that H5, H6, ad H7 were not read correctly by my
>>> programmer. H3 also shows full FF's, but H1 read as full 00's...Could it
>>> be
>>> that H1 is the only one that is indeed dead?
>>> 
>>> I'll remove the two 6520 PIAs, and I'll take a look on VCF for the
>>> voltages
>>> thread.
>>> 
>>> Thanks again for your time.
>>> 
>>> Phil
>>> 
>>> On May 14, 2011, at 3:17 AM, MikeS wrote:
>>> 
>>>> Sorry, emails crossed and you answered my question before I asked it ;-)
>>>> 
>>>> A crude way would be to measure the voltage on the various 6502 pins,
>>>> especially the Reset, Sync and Ready pins.
>>>> 
>>>> There's a thread on VCF right now that might be relevant.
>>>> 
>>>> m
>>>> 
>>>> ----- Original Message ----- From: "Philip Lord" <random6000@mac.com>
>>>> To: <cbm-hackers@musoftware.de>
>>>> Sent: Friday, May 13, 2011 1:55 PM
>>>> Subject: Re: PET 2001 fix Part 3 - RAM/ROM board etc.
>>>> 
>>>> 
>>>> Thanks André,
>>>> I only have limited tools. Logic probe, eprom burner and multimeter.
>>>> 
>>>> I'll have to snag the keyboard out of my working pet to try the 'LOAD'
>>>> test.
>>>> What other ways can I test if the CPU is working?
>>>> 
>>>> Phil
>>>> 
>>>> 
>>>> On May 14, 2011, at 2:39 AM, André Fachat wrote:
>>>> 
>>>>> 
>>>>> 
>>>>> Looking at the further discussion, you are concentrating on the video
>>>>> part, but is the CPU actually running ok? I didn't see that, may be I
>>>>> overlooked it. But you mentioned burning new ROMs as the original ones
>>>>> were dead.
>>>>> 
>>>>> If the cpu is not running ok, this could explain the random characters
>>>>> on
>>>>> one side and also the "snow", as some random code would not wait for
>>>>> the
>>>>> vertical retrace when writing to the screen memory.
>>>>> 
>>>>> Did you try checking for example with a tape and typing LOAD and
>>>>> pressing
>>>>> the Play button that the tape starts turning?
>>>>> 
>>>>> I'd concentrate finding why the CPU isn't working and looking at the
>>>>> video later.
>>>>> 
>>>>> André
>>>>> 
>>>>> 
>>>>> -------- Original-Nachricht --------
>>>>>> Datum: Fri, 13 May 2011 19:27:34 +0200
>>>>>> Von: "André Fachat" <afachat@gmx.de>
>>>>>> An: cbm-hackers@musoftware.de
>>>>>> Betreff: Re: PET 2001 fix Part 3 - RAM/ROM board etc.
>>>>> 
>>>>>> 
>>>>>> -------- Original-Nachricht --------
>>>>>> 
>>>>>>> So now I have a screen of random and slightly deformed characters
>>>>>>> (seems
>>>>>>> like the same or similar character layout on each start up though),
>>>>>>> with
>>>>>> a
>>>>>>> pixel flicker through them. I've put pics and a short video up on the
>>>>>> same
>>>>>>> page here:
>>>>>> 
>>>>>> Sorry to chime in so late only. The pixel flicker might be from the
>>>>>> fact
>>>>>> that the CPU accesses the video RAM. The oldest PETs had video RAM
>>>>>> with
>>>>>> max
>>>>>> 1MHz operation only, so when the CPU accesses the video RAM the video
>>>>>> display presented "snow". The CPU controlled access to the video RAM
>>>>>> by
>>>>>> sampling
>>>>>> the vertical retrace on a VIA pin (VIA Port B ($e840, 59456), bit 5).
>>>>>> This
>>>>>> could relate to the fact that characters seem stable when the machine
>>>>>> resets (switching off?)
>>>>>> 
>>>>>> Maybe the VIA has a problem here?
>>>>>> 
>>>>>> On a side note: the fact that switching this vertical retrace off
>>>>>> resulted
>>>>>> snow, but also faster screen output - no wait anymore - a certain POKE
>>>>>> was
>>>>>> found to make that VIA input pin an output - accidentally destroying
>>>>>> some
>>>>>> newer models, the "killer poke".
>>>>>> 
>>>>>> André
>>>>>> 
>>>>>> -- 
>>>>>> NEU: FreePhone - kostenlos mobil telefonieren und surfen!
>>>>>> Jetzt informieren: http://www.gmx.net/de/go/freephone
>>>>>> 
>>>>>>    Message was sent through the cbm-hackers mailing list
>>>>> 
>>>>> -- 
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>>>>> 
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>>>> 
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Received on 2011-05-14 10:00:19

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