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Ast Advantage! 16bit memory board causes 5170 not to boot when selecting two banks

offensive_Jerk

offensive_Jerk

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I have an AST Advantage board that I've been using in one of my AT systems. It's been working fine using the first bank with 64k chips. The first bank is 128k and using that to backfill the base memory to 640k on the 5170. (512k on board on the 5170.)

I decided to put more memory in the board so I can have some memory beyond base. I filled the second bank with 256k chips NMBS AAA2801P-08. I then set the Switch block 1 accordingly to tell the card I have two banks filled, one with 64k chips at 128k in the bank, and the other bank used and being filled with 256k chips at 512k. This caused the computer to not boot, nothing on screen. Hard drive seems to spin up, but nothing else happens. I have an aftermarket PSU in the system, so that didn't shut down. Not sure if the official IBM PSU would have shut down or not.

I also tried some MOSTEK MK4564 chips. Same thing.

I then tried removing the chips from the second bank, and leaving the switch settings as configured for the second bank filled and the computer still didn't boot......... So even with no ram fitted in bank 2, and having the switches set to use bank 2, the computer doesn't post.

I then tried filling all 3 banks with RAM and configuring the switches that way, but still no boot.

If I leave all RAM in, and change the switches back to only use the first bank, it will then boot again.

I noticed there are tantalum caps by each chip of memory. Is it possible one of these shorted out and when I tell the card to use the second bank, it shorts out causing the computer not too boot? No idea why else it would do this.

Seems to be basically whenever I move SW1 to ON it fails to post.

(Thanks to Modem7 for the manual.)
astadvantage.jpgastadvantage.jpg

astadvantage.PNG
 
I would be really surprised if a bypass capacitor is switched in or out of circuit depending on RAM setting. A shorted supply usually brings down the whole power supply anyway, so no hard disk, no leds, no fans, nothing.
I put my money on address conflict with the motherboard memory. Thre's no need to populate with actual RAM a row to make a conflict with motherboard's RAM as long as the data bus transceivers are enabled. So you have to understand how these rows are mapped in the actual address space to understand what you can enable without going into conflicts.

Frank IZ8DWF
 
I set the card how the instructions say, and it doesn't boot. If I set the address starting at 1024, I get a memory mismatch and lose the 128 of base memory and the system only counts to 512k.

I set jumper block #3 per the directions below since I have a 512k AT. I want the memory from the card to start at 512k. I set the block as directed to On,On,On,On,Off,On,On

I'll also mention I have only two cards installed, the Fixed Disk and floppy adapter, and a clone CGA card. I removed the network card and no change.


mem.PNG



Figure 3-5. Split Memory Addressing in a 512K AT
In this configuration, the first 128K of memory on the
Advantage! is dedicated to rounding out the AT's base
memory area to its 640K maximum.
• If the Advantage! has exactly 128K on it, this
memory is added to the 512K system board memory,
for total base memory of 640K. There would be no
expansion memory in the 15 MB extended memory area.
• If the Advantage! has more than 128K on it, the first
128K is used to round out net base memory to
640K, with the remaining Advantage! memory
addressed as expansion memory.
3-10
Configuration and Installation
The configuration described in Option #2 may be useful if you
are using application software which can access a full 640K
of base memory.
 
Even stranger, when I configure the card to NOT backfill the 128k, and use the entire card as expansion memory (1,152k) it works. After going into the Setup program and setting 512k base and 1,152 expansion memory, the system counts boots to "01664 KB OK" and seems to boot fine.

I don't get why it won't let me back fill the 128 with expansion memory. I can do either separately, but not both at once, which the card should be able to do. I wonder if the Persyst Color II cga card is conflicting? I'm stumped.
 
I installed a monochrome card and even pulled the Fixed Disk adapter.... Still won't boot with the backfill settings. This is turning out to be another useless memory card for the pile.
 
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