CompactFlash Adapter for Tandy 1400 Laptops

The CompactFlash Adapter for Tandy 1400 Laptops is a system specific XT-CF variant for Tandy 1400 Series Laptops:

• 1400LT models using BIOS version 2.51, and
• 1400FD/HD models using BIOS version 1.04

The board is programatically identical to the XT-CF-lite and is therefore powered by the XTIDE Universal BIOS, provided through an in-system re-programmable 32KB (addressible) flash-based ROM. Since the BIOS is only 8KB, 24KB is available for other purposes, and is byte-programmable.

Note: It is not currently known whether the 2.51 BIOS version can be used in earlier 1400LT models. The BIOS image is however available for download here.

To buy this and other PCBs, please visit the TexElec Store.

Specifications

General

• 8-bit Tandy 1400 Series Expansion Slot Card with CompactFlash header
• Entirely 5V CMOS logic
• Low-cost flash memory chip for boot ROM, with 32KB usable
• Port-mapped IO; supports both 8- and 16-bit instructions (via partial address decoding)
• Utilises XT-IDE Universal BIOS (XTplus build; adapter type: 'XT-CF')
• Fixed resource allocation - IO ports 300-31Fh, ROM 32KB at C800h
• Compatible with any CompactFlash card (microdrives are not supported due to power budget limitation from the Tandy 1400 expansion slot)

PCB

Bill of Materials

Part	Device	Package	Qty	Farnell	Mouser
IC1, IC2	74HCT688D	SOIC-20W	2	1085321	-
IC3	74HCT139D	SOIC-16	1	9591834	-
IC4	AMIC - A29010-70F	DIP-32	1	1907092	-
R1, R2, R4	10k Resistor	0603	3	1469748	-
R3	Do not populate	-	-	-	-
R5*	1k6 Resistor	0603	1	2138367	-
C1..5	0.1uF Ceramic Capacitor	0603	5	1414610	-
C6	10uF Electrolytic Capacitor	E2-5	1	8767084	-
CF1	3M NE750-Q516RB-50 CompactFlash Header	-	1	1267444	-
IC Socket	-	DIL32	1	1654375	571-1-390263-2
JP1, LED*	AMP - 826629-2	1x2 Pin Header	2	3418285	-

*Components only needed if activity LED is required

• Board design permits the use of a range of DIP-32 flash chips (1, 2 or 4Mb):
  • SST39SF0x0A (SST39SF010A, SST39SF020A, SST39SF040A)
  • AMIC A29010
• Regardless of the chip used, 32KB is presented commencing C800h

Configuration

• JP1: ROM enable (closed = enabled)
• An external LED can be attached to the 2-pin LED header, but a low-current type must be used (approx. 2mA available).
• The IO port address (300h - 31Fh) is fixed, as is the ROM address (32KB at C800h) - note therefore the board cannot co-exist with the Tandy 1400HD MFM disk controller
• Pre-configured BIOS based on XTIDE Universal BIOS r567 is available here
• The flash ROM can be programmed with the Lo-tech XT-CF flash utility

See Also

• lo-tech XT-CF Boards
• Tandy 1400 Series Laptops