Tandon BIOS Post Codes - BIOS Central

01	Test 80286 CPU flags and registers
02	Test BIOS ROM checksum
03	Test MC 146818 CMOS RAM battery - real time clock
04	Test 8254 programmable interrupt controller
05	8254 programmable interrupt controller test failed
06	Initialize RAM refresh
07	Test first 16K RAM
08	Initialize cold boot interrupt vectors
09	Test 8259 programmable interrupt controller and interrupt vectors
0A	Fill in temporary interrupt vectors
0B	Initialize interrupt vector table 1
0C	Initialize interrupt vector table 2
0D	Initialize fixed disk vector
0E	Interrupt vector test failed
0F	Clear keyboard controller input buffer
10	Keyboard controller input buffer clearing failed
11	Run keyboard controller self test
12	Initialize equipment check data area
13	Determine presence of and install 80287 math coprocessor
14	Test MC 146818 CMOS RAM disk value range
15	Test for and install parallel port
16	Test for and install serial port
17	Call interrupt 19 boot loader

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Tandon Type B AT 1992 BIOS Post Codes:

01	Cold boot started
06	Initialize chipset if any
07	Warm boot entry; Start of 8042 keyboard controller self test
08	Part of cold boot keyboard initialization passed
09	Keyboard self test passed; Test CMOS checksum
0A	Test CMOS RAM battery
0B	Save CMOS RAM battery condition in CMOS diagnostic/status register
0C	Finished saving CMOS RAM battery condition
0D	Test 8254 programmable interrupt timer; Disable RAM parity, I/O parity, DMA controllers and system speaker; Enable timer channel 2
0E	8254 programmable interrupt timer test failed, xx is the failing channel number
0F	Initialize 8254 programmable interrupt timer channels; Conduct memory refresh test
10	Refresh test failed
11	Test base 64K RAM and fill with zeros
12	64K RAM test failed - 3 long beeps and system halt
13	64K RAM test passed
14	Set up stack; Disable mappers for systems that support EMS drivers; Initialize battery beep flag parameters for notebook; Perform read/write test of CMOS RAM; Enable error message if failed
15	CMOS RAM read/write test complete
16	Calculating CPU speed; May set to low if CMOS RAM failed
18	Test and initialize both 8259 programmable interrupt controllers
1A	8259 programmable interrupt controllers initialization complete
1B	Install interrupt handler and vector for interrupt 0F to check for unexpected interrupts; Halt is unexpected interrupt occurs
1C	Unexpected interrupt did not occur; Test 8254 programmable interrupt timer channel 0, IRQ 0 and software interrupt 8 tests
1D	Error; Timer 0 interrupt did not occur when expected, system is halted
1E	Both 8259 programmable interrupt controllers passed the tests
20	Set up interrupt vectors 02-1F
21	Set up interrupt vectors 70-77
22	Clear interrupt vectors for 41 and 46
23	Read 8042 keyboard controller self test result; DMA page register channel 2
24	Test for proper 8042 keyboard controller self test result
25	Error; Keyboard controller self test failed; System id halted with message displayed
26	Keyboard controller self test passed
27	Confirm DMA working; Prepare DMA channel 2 for floppy data transfer
28	Reinitialize video
29	Reinitialize video with cursor off
2A	Video parameters are initialized
2B	Enable NMI and I/O channel check; Disable 8254 programmable interrupt timer channel 2 and speaker
2C	Run RAM test to determine size of RAM
2D	RAM sizing complete
2E	Send reset command to keyboard controller to initialize a keyboard scan cycle
2F	Keyboard has been initialized; Initialize CMOS real time clock
30	CMOS real time clock has been initialized; Initialize on board floppy if any
31	Install the hard disk controller
32	Disk controller has been initialized; Prepare DMA channel 2 for floppy transfers
33	Perform equipment check and initialize math coprocessor
34	Install the serial and parallel ports
35	Test CMOS RAM battery
36	Check for keystroke
37	Enable 8254 programmable interrupt timer channel 0 for system tick; Enable keyboard and slave interrupt controller 8259 programmable interrupt controller 2
38	Timer tick, keyboard and 8259 programmable interrupt controller 2 have been initialized; Enable/disable cache through CMOS RAM
39	Enable keyboard interface and interrupts; Go to built in setup program as necessary; Shadow ROM's found
3A	Set up complete
3B	Test the hard disk and floppy disk
3C	Scan for and invoke the adapter ROM's in C800-E000
3D	Turn of gate A20; Restore vectors 3bh-3fh with temporary interrupt service routines
3E	Gate A20 turned on
3F	Call interrupt 19 boot loader

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Tandon 486 EISA 1989 BIOS Post Codes:

01	Disable cache, enable ROM, high speed on, turn off cache's, disable EISA NMI's, set master/slave IRQ's to edge triggered, disable reset chaining; Disable 82C601 chip
05	Initialize address decoder, 640K RAM; Set BIOS as cacheable, enable extended memory
06	Clear shutdown flag
07	8042 keyboard controller test; Wait till 8042 buffer empty; Disable 8042 command, read 8042 output buffer; Set response ok to DMA page register channel 2
08	Send 8042 keyboard controller NOP command; Get 8042 self test result; Send DMA page register channel 2; If xx=55, then self test ok
09	Test BIOS ROM checksum
0A	Read CMOS registers 3 times to clear pending CMOS real time clock interrupts; Disable real time clock interrupts; Check battery
0B	Bad CMOS RAM battery
0C	Send command to port 61 to disable parity and speaker
0D	Test 8254programmable interrupt timer counter
0E	One of the counter timers is bad; xx indicates the bad counter
0F	Enable and check memory refresh
10	Memory refresh failed
11	Check and clear the first 64K RAM in real mode; Disable NMI; Clear parity latches; Fill 64K with 5555 and check it, then AAA and check it, then 0000
12	First 64K RAM memory test failed
13	First 64K RAM memory test passed
14	Reset the warm boot flag and test CMOS RAM; Turn off caches; Shadow the BIOS; set high speed; Calculate high speed and initialize GP flag; Set low speed and turn off cache if CMOS not good or CMOS speed not high
16	Check shutdown flag 123x
17	Reset was cold boot
18	Prepare 8259 programmable interrupt controllers
19	8259 programmable interrupt controllers initialization failed; Initialize video and display the error message
1A	Test 8259 programmable interrupt controller
1B	Set interrupt 0F to unexpected interrupt vector; Enable timer and interrupt
1C	Set interrupt 08 to timer 0 interrupt vector
1D	Timer interrupt did not occur; Initialize video and display error message
1E	Initialize interrupt vectors
1F	Initialize interrupt vectors 00-6F to temporary interrupt service routines
20	Set vectors for interrupt 02-1F
21	Set interrupt vectors for 70-77, clear vectors 60-67 and 78-FF
22	Clear interrupt vectors for 41 and 46
23	Read 8042 keyboard controller self test results from DMA page register channel 2
24	Test for proper 8042 keyboard controller self test result
25	8042 keyboard controller self test failed
26	Initialize 8042 keyboard controller
27	Check shutdown flag=123x; If no=cold boot
28	If cold boot or CMOS RAM is bad, then install video ROM and initialize video; Initialize equipment flags according to primary video adapter and CMOS RAM content; Initialize POST status
29	If not cold boot and CMOS RAM ok; Install video ROM and initialize video for mono/CGA; Initialize equipment flags according to primary video adapter and CMOS RAM contents
2A	Check for bad CMOS RAM
2B	Check shutdown flag=123x
2C	If cold boot; Turn off caches; Test memory for size and reinitialize cache status
2D	Turn off "POST fail" CMOS RAM bit and display and error messages; Initialize keyboard RAM
2E	Initialize 8042 keyboard controller and test keyboard
2F	Initialize time of day in real time clock
30	Test for and install floppy drive controller
31	Enable 82C601 IDE interface; Test for and install hard disk
32	Test 8259 programmable interrupt controller DMA registers with 55 then AA, then initialize them to 00
33	Test for and initialize math coprocessor
34	Test for and initialize parallel and serial ports
35	Initialize RAM variables for bad CMOS time, date, checksum and battery
36	Wait for user to press Esc or Space; Check for keyboard lock; Clear keyboard lock override; Beep to indicate speed; Display error messages
37	Enable system clock tick (IRQ 0); Enable keyboard (IRQ 1); Enable slave interrupt controller (IRQ 2)
38	Initialize RAM variables for Ctrl-Alt_Esc
39	Enter setup is keystroke pressed
3A	Clear screen and update equipment flags according to CMOS RAM contents; Shadow ROM's; Enable/disable cache through CMOS RAM
3B	Initialize floppy and hard drives
3C	Set POST failed bit in CMOS RAM; Scan for and initialize adapter ROM's
3D	Clear the shutdown flag to 0; Disable gate A20 and enable memory wrap in real mode
3E	Set vectors for interrupts 3B-3F; Clear post fail bit in CMOS RAM
3F	Call interrupt 19 boot loader

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