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| IMPORTANT: | The following is specific to the IBM 5160 (IBM XT), fitted with IBM BIOS ROM's. |
| Certain portions will not be applicable to clones that were made of the IBM 5160. |
| Error / Symptom | Description | ||||
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| [ Nothing ] | Even after two minutes, nothing on-screen, no beep/beeps were heard from the speaker, and no attempt was made to access the A: drive. It appears (repeat: appears) that the motherboard is dead. Understandably, this symptom has many many causes. First, rule out the following possibility: 11/08/82 BIOS fitted on motherboard, and IBM CGA card fitted, but motherboard's SW1 switches are set to MDA. I suggest that you try the Minimum Diagnostic Configuration procedure at here. Also, consider the use of a diagnostic ROM in motherboard ROM socket U18 (i.e. in place of the first of the two IBM BIOS ROM's): • Supersoft/Landmark diagnostic ROM • Ruud's diagnostic ROM |
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| Flashing cursor displayed on-screen, nothing else (no beeps, nothing), even after two minutes. | • On an IBM 5160 fitted with the 11/08/82 version of motherboard BIOS, a known cause is having an IBM MDA video card fitted, but the motherboard's SW1 switches are set to CGA. • I once saw this when an IBM MDA card was not properly seated in its slot. |
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Flashing cursor displayed on-screen, no RAM count-up, no error beeps, but if you wait long enough, the computer will attempt to boot from A: drive |
On the IBM 5160, a known cause is having an IBM MDA video card fitted, but the motherboard's SW1 switches are set to EGA. If the IBM 5160 has the 05/09/86 version of motherboard BIOS fitted, then another possibility is having an IBM CGA video card fitted, but the motherboard's SW1 switches are set to EGA. |
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RAM count-up is seen, then the screen clears showing an underline cursor, then the floppy drive's LED and spindle motor turn on, but never turn off. No futher progress. |
I have sometimes seen this symptom when: 08/16/82 or 11/08/82 BIOS fitted, and the U19 ROM is removed. |
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| Continuous beep | The POST does not output a continuous beep. Known causes: • Faulty motherboard. • Faulty expansion card (faulty in a way that interferes with motherboard operation). • Faulty power supply. |
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| 1 long beep then 2 short beeps | Some causes: • 5160 motherboard - Configured via SW1 for an MDA video card, but either the POST cannot find an MDA video card to initialise, or the MDA card is faulty. • 5160 motherboard - Configured via SW1 for an CGA video card, but either the POST cannot find an CGA video card to initialise, or the CGA card is faulty. • A video card with a BIOS expansion ROM did a self test and found a problem with itself. |
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| 1 long beep then 3 short beeps | The BIOS expansion ROM on an IBM EGA card is known to generate this if it discovers that the card has faulty RAM. |
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| 1 short beep | For an IBM 5160, not an error; it is the 5160's POST indicating that the POST successfully executed. (The POST will then attempt to boot to disk or Cassette BASIC.) |
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| 2 short beeps | For an IBM 5160, when an xx01 error (101, 201, etc., per below) is displayed on-screen, normally accompanying that display is 2 short beeps, and "ERROR. (RESUME = F1 KEY)" |
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| 101 displayed on-screen |
Some possible 101 causes: • Motherboard's 8259 interrupt controller chip (includes supporting chips). • Motherboard's 8253 timer chip (includes supporting chips). • Motherboard's 8237 DMA controller chip (includes supporting chips). NOTE: For detail, see actions '8259 TEST' and 'TEST/SET TIMER 0' and 'DMA TC0' at here. |
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| 201 displayed on-screen (xxxxx xx 201) |
RAM related error. For the 5160, the 201 will be prefixed by an address and a byte (e.g. "30000 10 201"). Some possible 201 causes: • 5160 motherboard - failure of a RAM chip. (And there may be more than one failure.) • 5160 motherboard - RAM chip has poor connection to the motherboard. • 5160 motherboard - failure of the circuitry that supports RAM. • 5160 motherboard - incorrect switch settings. • 5160 motherboard - incorrect type of RAM chip fitted. • 5160 motherboard - printed circuit board (PCB) problem (bad solder joint, damaged traces, damaged IC socket). • RAM expansion card - failure of its RAM or circuitry. • RAM expansion card - incorrect switch settings. Note: Faulty RAM refresh circuitry may not result in a 201 error on an IBM 5160. See here. More information on IBM 5160 RAM at here. |
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| 301 displayed on-screen (301) (xx 301) |
Keyboard related error. If the "301" is preceded by a byte, e.g. "23 301", then the keyboard's self test is indicating to the POST that a key is 'stuck' down. The byte indicates which key (see here). If the "301" is not preceded by a byte, then it's a general keyboard error. Possible causes: • No keyboard attached. • AT class keyboard attached. That will not work. A PC/XT class keyboard is required. • Faulty keyboard - broken wire in cable. • Faulty keyboard - wire loose in connector. • Faulty keyboard - chip failure. • Faulty motherboard - bad solder joint on DIN connector for keyboard. • Faulty motherboard - some cases of faulty keyboard circuitry. A related diagram is at here. |
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| 601 displayed on-screen | Examination of a floppy drive failed: 1982 dated motherboard BIOS': Only tests drive A: (physical drive 0). 1986 dated motherboard BIOS': Tests as many floppy drives as indicated by switches 7 and 8 on motherboard switch bank SW1. Some possible 601 causes: • Floppy controller card - faulty. • Floppy controller card - dirty edge connectors. • Floppy controller card - not seated correctly in motherboard's expansion slot. • Motherboard - edge connector contacts in expansion slot are dirty/damaged. (Try a different slot.) • Motherboard with 1986 dated BIOS - SW1 switches not set correctly for the number of floppy drives fitted. • Floppy cable - faulty. • Floppy cable - not the correct type for a 5160 - see here. • Floppy cable - not fitted correctly - see here. • Floppy drive - missing. • Floppy drive - faulty. • Floppy drive - drive select jumper not set properly - see here. • Floppy drive - not compatible. • Floppy drive - compatible, but not configured correctly for a 5160. • Floppy drive - some cases of improper termination. |
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| 1701 displayed on-screen | This error is not generated by the motherboard's POST, but by the initialisation code within a BIOS expansion ROM residing on an XT-class hard disk controller. The maker of the particular XT-class hard disk controller decides in which situations they have their controller display the "1701" error. 1701 is typically a very high level error, indicating a problem with the hard drive system (system = controller + cables + drive + configuration + power). So, lots of possible causes. See here for some ideas. |
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| 1801 displayed on-screen | The POST found an extender card for the IBM 5161 Expansion Unit within the 5160. Because of that, the POST made an assumption that a 5161 Expansion Unit is connected to the card. The POST attempted to communicate with the 5161 and that communication failed. Related diagram at here. Some possible 1801 causes: • 5161 Expansion Unit - not connected to the extender card in the host computer (e.g. missing cable) (e.g. loosely connected cable). • 5161 Expansion Unit - not powered on (should to be powered on before the host computer is). • 5161 Expansion Unit - faulty system board (backplane). • 5161 Expansion Unit - power supply - faulty. • 5161 Expansion Unit - power supply - has shut down due to a fault elsewhere in the 5161. • 5161 Expansion Unit - power supply - has shut down due to inadequate loading. • Cable - faulty. • Cable - oxide build-up on the contacts within the two connectors. • Extender card - faulty. • Extender card - not seated correctly in host computer's ISA slot, or poor connection (e.g. dirty contacts). • Extender card - oxide build-up on the contacts within the cable connector. • Receiver card (within 5161) - wrong type. See here for a photo of the correct type. • Receiver card (within 5161) - faulty. • Receiver card (within 5161) - not seated correctly in 5161's ISA slot, or poor connection (e.g. dirty contacts). • Receiver card (within 5161) - oxide build-up on the contacts within the cable connector.
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| C8000 ROM displayed on-screen | An expansion card has a BIOS expansion ROM addressed at C8000, and that ROM is partially faulty or has corrupt contents, or has poor connection to the card. C8000 is commonly used by XT-class hard disk controllers. |
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| CA000 ROM displayed on-screen | An expansion card has a BIOS expansion ROM addressed at CA000, and that ROM is partially faulty or has corrupt contents, or has poor connection to the card. CA000 is commonly used by third-party floppy controllers (those that have a BIOS expansion ROM). |
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| D0000 ROM displayed on-screen | An expansion card has a BIOS expansion ROM addressed at D0000, and that ROM is partially faulty or has corrupt contents. |
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| F6000 ROM displayed on-screen | Only the POST of the 08/16/82 and 11/08/82 BIOS generates this error. See note 1. This is one of four tests of Cassette BASIC code in ROM, this particular test specifically examining the 8 KB sized block starting at address F6000. Per here, that corresponds to part of motherboard ROM chip U19. Some possible causes: • Motherboard ROM chip U19 is missing. • Motherboard ROM chip U19 is faulty. • Motherboard ROM chip U19 has poor connection to the motherboard - try re-seating it in its socket. |
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| F8000 ROM displayed on-screen | Only the POST of the 08/16/82 and 11/08/82 BIOS generates this error. See note 1. This is one of four tests of Cassette BASIC code in ROM, this particular test specifically examining the 8 KB sized block starting at address F8000. Per here, that corresponds to part of motherboard ROM chip U18. Some possible causes: • Motherboard ROM chip U18 contents have become partially corrupt (in address range F8000 to F9FFF). • Motherboard ROM chip U18 has poor connection to the motherboard - try re-seating it in its socket. |
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| FA000 ROM displayed on-screen | Only the POST of the 08/16/82 and 11/08/82 BIOS generates this error. See note 1. This is one of four tests of Cassette BASIC code in ROM, this particular test specifically examining the 8 KB sized block starting at address FA000. Per here, that corresponds to part of motherboard ROM chip U18. Some possible causes: • Motherboard ROM chip U18 contents have become partially corrupt (in address range FA000 to FBFFF). • Motherboard ROM chip U18 has poor connection to the motherboard - try re-seating it in its socket. |
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| FC000 ROM displayed on-screen | Only the POST of the 08/16/82 and 11/08/82 BIOS generates this error. See note 1. This is one of four tests of Cassette BASIC code in ROM, this particular test specifically examining the 8 KB sized block starting at address FC000. Per here, that corresponds to part of motherboard ROM chip U18. Some possible causes: • Motherboard ROM chip U18 contents have become partially corrupt (in address range FC000 to FDFFF). • Motherboard ROM chip U18 has poor connection to the motherboard - try re-seating it in its socket. |
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| PARITY CHECK displayed on-screen | Intermittent and unlike below, there is no '1' nor '2' following 'PARITY CHECK'. A computer virus is known to display this. (The IBM BIOS in an IBM 5160 always displays a 1 or a 2 after PARITY CHECK.) |
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| PARITY CHECK 1 displayed on-screen | A parity error occurred when an address in motherboard RAM was read. Related diagram at here. Some possible causes: • 5160 motherboard - RAM chip failure. • 5160 motherboard - A RAM chip (possibly multiple) has a poor connection to the motherboard. • 5160 motherboard - bad parity generation circuitry. • 5160 motherboard - bad RAM refresh circuitry. • 5160 motherboard - bad filter capacitor/s close to the RAM chips. (Of those, suspect the tantalum type ones before the ceramic type ones.) • If intermittent, see note 2. |
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| PARITY CHECK 2 displayed on-screen | A parity error occurred when an address in expansion card hosted RAM was read. Related diagram at here. |
| Note 1 | In later motherboard BIOS revisions (the 1986 dated ones), the POST checks U18 and U19 very early, and if either U18 or U19 are found faulty, the POST simply halts the CPU (without displaying anything first). |
| Note 2 | If intermittent: • Verify that the mains AC power (house power) fed to the computer is within specification and stable. Someone on the Vintage Computer Forums indicated that the cause of their intermittent PARITY CHECK errors was their air conditioner (when the compressor kicked in/out). • The computer's power supply may be the cause. • Bad RAM chip/s may be the cause. • Bad RAM support circuitry may be the cause. (One example: bad filter capacitor/s close to the RAM chips.) • In case of poor electrical contact, try re-seating the RAM chips in their sockets. |
