The two missing chips are OK. The chip missing on the far left is the 8087 numeric coprocessor, and the chips missing in the center is an ROM extension for an integrated BASIC.

PC/XT-class computers used a different kind of keyboard than AT-class computers, even if both types of keyboards have a 5-pin DIN plug. You likely need to find a PC/XT-compatible keyboard to get your system working.

mkarcher wrote on 2025-01-26, 14:31:

The two missing chips are OK. The chip missing on the far left is the 8087 numeric coprocessor, and the chips missing in the center is an ROM extension for an integrated BASIC.

PC/XT-class computers used a different kind of keyboard than AT-class computers, even if both types of keyboards have a 5-pin DIN plug. You likely need to find a PC/XT-compatible keyboard to get your system working.

Can the way i identify AT from XT keyboards is by the middle-ish enter key and shift key?

There are also XT-AT switchable keyboards.

Ron Philips wrote on 2025-01-26, 14:40:

Can the way i identify AT from XT keyboards is by the middle-ish enter key and shift key?

There are both XT-compatible and AT-only keyboards with 101 (US)/102 (EU) keys. In the late 80s and early 90s, a lot of keyboards supported both the XT and the AT protocol, either auto-detecting the host type or having a physical switch. Probably getting an XT-compatible 101-key keyboard is the cheapest and easiest option.

The image you quote is correct in pointing out some differences between the IBM model F keyboard for the XT and the IBM model F keyboard for the AT, so in some way of thinking, the picture is "correct". On the other hand, placing a key between the left shift key and the "Z" key is not only done on the XT variant of the IBM model F keyboard, but that spot is also used on the "international" edition of AT-like keyboards. The shape of the "Enter" key of the model F XT keyboard is quite unusual and distinct, but I wouldn't count on it being a clear indicator of XT compatibility on anything but an IBM-branded keyboard.

If we look at vintage keyboards without a dedicated cursor key block, look for the SysRq key: If that key is missing, you likely deal with an XT-only keyboard. On the other hand, of the SysRq key is present on a keyboard without the dedicated cursor keys, you likely deal with a very early AT keyboard (all later keyboards use the "enhanced layout", aka 101/102-key keyboards). I wouldn't expect an AT keyboard that early to include XT compatiblity. The dual-mode keyboards likely became a thing when computers with dedicated cursor keys looked "more advanced" than computers without, so there was a demand to sell (not that advanced) XT computers with the advanced-looking enhanced AT keyboard. Which is not just misleading consumers, as Turbo XTs were quite as good as early ATs for many tasks at that time, and the dedicated cursor keys made using the computer, especially when entering numbers in a spreadsheet more convenient.

Also, the original PC/XT keyboard did not have Num/Caps indicators at all on the keyboard. There is no way for the computer to tell an XT keyboard whether the LED should be on or off. There are non-IBM XT keyboards (and XT/AT-multi-protocol keyboards) that have "working" Num/Caps indicators on the keyboard. These Keyboards just toggle the LED whenever you press the corresponding lock key, and can get out of sync with the PC if the PC (for example running a game with a custom keyboard handler) does not process the lock key by toggling the associated keyboard status bit in the BIOS data area.

mkarcher wrote on 2025-01-26, 15:08:

There are both XT-compatible and AT-only keyboards with 101 (US)/102 (EU) keys. In the late 80s and early 90s, a lot of keyboard […]
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Ron Philips wrote on 2025-01-26, 14:40:

Can the way i identify AT from XT keyboards is by the middle-ish enter key and shift key?

There are both XT-compatible and AT-only keyboards with 101 (US)/102 (EU) keys. In the late 80s and early 90s, a lot of keyboards supported both the XT and the AT protocol, either auto-detecting the host type or having a physical switch. Probably getting an XT-compatible 101-key keyboard is the cheapest and easiest option.

The image you quote is correct in pointing out some differences between the IBM model F keyboard for the XT and the IBM model F keyboard for the AT, so in some way of thinking, the picture is "correct". On the other hand, placing a key between the left shift key and the "Z" key is not only done on the XT variant of the IBM model F keyboard, but that spot is also used on the "international" edition of AT-like keyboards. The shape of the "Enter" key of the model F XT keyboard is quite unusual and distinct, but I wouldn't count on it being a clear indicator of XT compatibility on anything but an IBM-branded keyboard.

If we look at vintage keyboards without a dedicated cursor key block, look for the SysRq key: If that key is missing, you likely deal with an XT-only keyboard. On the other hand, of the SysRq key is present on a keyboard without the dedicated cursor keys, you likely deal with a very early AT keyboard (all later keyboards use the "enhanced layout", aka 101/102-key keyboards). I wouldn't expect an AT keyboard that early to include XT compatiblity. The dual-mode keyboards likely became a thing when computers with dedicated cursor keys looked "more advanced" than computers without, so there was a demand to sell (not that advanced) XT computers with the advanced-looking enhanced AT keyboard. Which is not just misleading consumers, as Turbo XTs were quite as good as early ATs for many tasks at that time, and the dedicated cursor keys made using the computer, especially when entering numbers in a spreadsheet more convenient.

Also, the original PC/XT keyboard did not have Num/Caps indicators at all on the keyboard. There is no way for the computer to tell an XT keyboard whether the LED should be on or off. There are non-IBM XT keyboards (and XT/AT-multi-protocol keyboards) that have "working" Num/Caps indicators on the keyboard. These Keyboards just toggle the LED whenever you press the corresponding lock key, and can get out of sync with the PC if the PC (for example running a game with a custom keyboard handler) does not process the lock key by toggling the associated keyboard status bit in the BIOS data area.

Could this be?

Seems like your keyboard is XT-AT switchable, just the switch is marked as "80286,80386|8088" instead of "AT|XT".

Ron Philips wrote on 2025-01-26, 16:12:

Could this be?

Yeah, just slide the switch to the right position (marked "8088") to get the keyboard into PC/XT mode. analog_programmer is correct. If the keyboard doesn't work in XT mode, we actually need to start troubleshooting your system.

At last, the keyboard error is gone from startup and i can navigate the system now. Thanks to you guys both you saved me so much trouble I really appreciate it.