#1 MEG Ram Expansion
6 messages in this thread
Dave,
I upgraded my Amiga last night to 1 meg last night. Thanks for posting the
correction. I would not have noticed it. Works great! I made one mistake. I
nicked the wire from pin 3 on U1H (74F138) to pin 10 U1J (74F399) and it broke
without my noticing it. It would boot under 1.1 but not 1.2. Would crash with
addmem, otherwise ran fine in 512K mode. Replaced wire and everything was
fine.
Question, why does avail give the following results when system is booted
with 1.2 and 1.1 with addmem C00000 C7FFFF respectively?
Wb1.2 Wb1.1
Maximum Maximum
Chip 523232 524288
Fast 516888 524280 (not a typo)
Total 1040120 1048568
Thanks again for the upgrade info!
John Y.
John,
The reason for the "524280" must be that 8 bytes are used in FAST memory to
store some information after an addmem is done under 1.1
With autoconfig, of course, there is even more taken away since a lot of
system stuff gets loaded directly into FAST.
Regards, Larry.
Larry,
I thought that the column label maximum in avail meant the total
physical memory, not unallocated. Am I confused? Not much memory to quibble
over, just want to be sure everything is ok. Thanks.
John
John,
I don't remember what it did under 1.1 on my machine, but an AVAIL under 1.2
seems to give you a maximum that is really the maximum available for allocation
after boot-up. Notice the maximums in your example under 1.2, where you have
523232 CHIP and 516888 FAST. If this were indeed the maximum of all memory, the
numbers would be 524288 and the total would be 1048576.
Regards, Larry.
What is this 1 MEG expansion you guys have been talking about?
Browsing through the messages, this caught my eye, but I don't seem to be
able to trace it back to the source.
I'd really like some information on this.
Thanx,
DonC
Not sure which thread you got in on Don, but the most recent discussion has
been about an internal mod that adds 512K by piggybacking the extra chips onto
the internal 256. Dave Haynie improved on the original by uploading a circuit
that causes the extra memory to autoconfigure.
All the associated files are in DL 11.
Regards, Larry.