[Coco] Did this really happen?

[M. David Johnson]

Thanks Art -

I tried the 62000/72000 last night 
and noted there was no 
differentiation. 

But I got the general idea and did 
this, which did work and does seem 
to confirms that I do indeed have 
512K.

I'm not completely sure what the
results mean in detail though.

1000 '*****
1010 '*
1020 '* MSIZCHEK.BAS
1030 '* MDJ 2021/09/05
1040 '*
1050 '* 512K MEMORY SIZE CHECK
1060 '*
1070 '* WITH THANKS TO
1080 '* ART FLEXER
1090 '* FOR POINTING OUT THE
1100 '* THE GENERAL CONCEPT
1110 '*
1120 '*****
1130 '
1140 'POKING INTO MEMORY
1150 LPOKE &H8A3E,31
1160 LPOKE &H18A3E,62
1170 LPOKE &H28A3E,93
1180 LPOKE &H38A3E,124
1190 LPOKE &H48A3E,155
1200 LPOKE &H58A3E,186
1210 LPOKE &H68A3E,217
1220 LPOKE &H78A3E,248
1230 '
1240 'PEEKING AND REPORTING
1250 V = LPEEK(&H8A3E)
1260 PRINT "&H08A3E ";V
1270 V = LPEEK(&H18A3E)
1280 PRINT "&H18A3E ";V
1290 V = LPEEK(&H28A3E)
1300 PRINT "&H28A3E ";V
1310 V = LPEEK(&H38A3E)
1320 PRINT "&H38A3E ";V
1330 V = LPEEK(&H48A3E)
1340 PRINT "&H48A3E ";V
1350 V = LPEEK(&H58A3E)
1360 PRINT "&H58A3E ";V
1370 V = LPEEK(&H68A3E)
1380 PRINT "&H68A3E ";V
1390 V = LPEEK(&H78A3E)
1400 PRINT "&H78A3E ";V
1410 '
1420 'EXIT
32767 END

Results:
                       PEEKS
               ----------------------
                   VCC     REAL COCOS
               ----------  ----------
ADDRESS  POKE  128K  512K  128K  512K
-------  ----  ----  ----  ----  ----
&H08A3E    31   217    31   217    31
&H18A3E    62   248    62   248    62
&H28A3E    93   217    93   217    93
&H38A3E   124   248   124   248   124
&H48A3E   155   217   155   217   155
&H58A3E   186   248   186   248   186
&H68A3E   217   217   217   217   217
&H78A3E   248   248   248   248   248

Thanks again.

Could you point me to something that
would explain the details?

--
M. David Johnson
mdj at bds-soft.com


-----Original Message-----
From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of Arthur Flexser
Sent: Sunday, September 5, 2021 10:51 PM
To: CoCoList for Color Computer Enthusiasts
Subject: Re: [Coco] Did this really happen?

Oops again!  The two addresses should be $72000 and $52000 (not $62000) for
a proper test--ghosting is to addresses $20000 apart (128K), not $10000
apart (64K).

Art

On Sun, Sep 5, 2021 at 10:31 PM Arthur Flexser <flexser at fiu.edu> wrote:

> Oops, Basic may mess with address 0, safer if you try it with $72000 and
> $62000 instead.
>
> Art
>
> On Sun, Sep 5, 2021 at 10:28 PM Arthur Flexser <flexser at fiu.edu> wrote:
>
>> A quick check for 512K is to see if values poked in "ghost" to other
>> addresses that are $10000 different.  For example,
>>
>> 10 LPOKE &H70000, 111
>> 20 LPOKE &H60000, 222
>> 30 PRINT LPEEK(&H70000), LPEEK (&H60000)
>>
>> If the values printed out by line 30 are both 222, you have 128K;  if
>> they are 111 and 222, you have 512K.
>>
>> (This is off the top of my head, somebody please correct me if I've made
>> a mistake here.  It's been quite a few years.  Try it on your 128K CoCo
as
>> well as the 512K (?) one to make sure this works properly.)
>>
>> Art
>>
>> On Sun, Sep 5, 2021 at 6:16 PM M. David Johnson <mdj at bds-soft.com> wrote:
>>
>>> Before I get too excited, I'd like someone, more proficient than I, to
>>> confirm my apparent unexpected blessing.
>>>
>>> I just purchased two 128K CoCo 3's off of ebay.
>>>
>>> The first one worked fine. It said "128K Color Computer 3" on the top,
>>> but
>>> just to confirm, I took a flashlight and looked through the top slots. I
>>> read MCM41464P on one of the chips (a 64K x 4 RAM I believe, implying a
>>> total 128K x 8 memory).
>>>
>>> When the second one arrived, it also said "128K Color Computer 3" on the
>>> top. But it had something rattling around loose inside the case. When I
>>> opened it up I discovered that it had empty sockets where I expected the
>>> RAM
>>> chips to be. And the thing rattling around loose was an L-shaped board
>>> with
>>> sixteen MCM6256AP12 chips on it (each a 256K x 1 RAM I believe, implying
>>> a
>>> total of 512K x 8 memory).
>>>
>>> After I said a quick "Thank You, Lord" under my breath, I re-seated the
>>> board in the headers provided on the motherboard, and closed the CoCo
>>> back
>>> up, I plugged it in and it too worked fine.
>>>
>>> Have I judged correctly?
>>>
>>> And, could the CoCo 3 512K Memory Checker available on the CoCo Archive
>>> be
>>> used to double-confirm this?
>>>
>>> --
>>> M. David Johnson
>>> mdj at bds-soft.com
>>>
>>>
>>> --
>>> Coco mailing list
>>> Coco at maltedmedia.com
>>> https://pairlist5.pair.net/mailman/listinfo/coco
>>>
>>

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