Memory Expansion on IBM XT-5160

[MaTel]

Hello,

today I want to expand the memory of my IBM-XT 5160 up to 640kb. But I have some troubble with that.

Hardware:
IBM-XT 5160 with 256KB on board ( 64-256KB Mainboard, BIOS 11/08/82 )

Memory Expansion ( Multi I/O ): Diamond Flower MF-100 ( look at Total Hardware ).
All memory Banks are equiped.
http://th99.dyndns.org/i/C-D/52500.htm

Problem:
I can't get more memory than 576kb (256kb on board + 320kb Expansion ). If I set the memory expansion unit to 384KB (256kb on board + 384kb Expansion = 640kb ) the memory count on system-startup stops at 256kb.


My jumper settings on Memory Expansion are:

JP3 Closed ( Parity check enabled )

Starting Memory Address Configuration:
256KB S1=On S2=Off S3=Off

Installed Memory Address Configuration:
256KB S4:On S5:Off S6:Off (works fine... 512kb recognized )
320KB S4:On S5:Off S6:On ( works fine... 572kb recognized )
384KB S4:On S5:On S6:On ( doesn't work... only 256kb recognized )


I think in "starting memory address configuration" I have to set the memory size on the mainboard ( 256KB ) and in "Installed Memory Address Configuration" I have to set the size of the memory expansion.

What is wrong in my configuration?

 

[frozenfire75i]

Are all your chips the same size and speed?

 

[MaTel]

yes. all memory-chips on the expansion board are the same.

 

[dongfeng]

Your settings look fine to me; maybe TH99 has some inaccurate switch settings? It wouldn't be the first time...

 

[modem7]

I'm thinking along the same lines as frozenfire75i. Something about bank 5 being switched in is causing the board to effectively disappear.

Could be one of the chips in bank 5 ?? If you remove the bank 5 chips (using anti-static techniques of course), leaving the switches set to all banks (384K=on/on/on), does the 5160 then count up to 576K (256K + 320K) instead of 256K ? If so, that would certainly suggest a chip problem.

 

[MaTel]

I'm thinking along the same lines as frozenfire75i. Something about bank 5 being switched in is causing the board to effectively disappear.

Could be one of the chips in bank 5 ?? If you remove the bank 5 chips (using anti-static techniques of course), leaving the switches set to all banks (384K=on/on/on), does the 5160 then count up to 576K (256K + 320K) instead of 256K ? If so, that would certainly suggest a chip problem.

Hmmm, I will test it at weekend.

 

[MaTel]

I'm thinking along the same lines as frozenfire75i. Something about bank 5 being switched in is causing the board to effectively disappear.

Could be one of the chips in bank 5 ?? If you remove the bank 5 chips (using anti-static techniques of course), leaving the switches set to all banks (384K=on/on/on), does the 5160 then count up to 576K (256K + 320K) instead of 256K ? If so, that would certainly suggest a chip problem.

I have removed the bank 5 chips but the 5160 does only count up to 256k (386k=on/on/on). Then I have change the bank 4 chips with bank 5 chips but...

any other ideas?

 

[MaTel]

Your settings look fine to me; maybe TH99 has some inaccurate switch settings? It wouldn't be the first time...

Yesterday I spent some more time for my memory problem. I look at the switch setting table on total hardware and saw a switch setting ( I saw it not really )

S5: ON S6:ON S7:OFF is not documented..... and.......


640KB !!! :mrgreen: