A2088 XT Bridge Board

A2088 Upgrades and modifications

A2088 Upgrade ROM

A new ROM revision has been issued to upgrade the A2088.
ROM - U28 - Part Number - 380788-06
This ROM fixes Auto-Configuration errors caused by some third part software and hardware.
This is an in-line change and is not covered under standard warranty. Dealer billing is $7.70.

Source: Commodore Techtopics 27/3-7.1 and 28/3-4.1

A2088 use external 1020 as drive A:

A2088 XT Emulator is configured to see the internal 5 1/4 drive as drive A:. Some customers are requesting that an external 5 1/4 be configured as drive A:. To modify the A2088 you must reverse the drive select signals .

Remove the A2088 Bridge card from unit. Locate IC U49 (74LS175), see page 26 in A2000 System Schematics.
Note: Pin 10 (*DRVSEL1) is tied to pin 1 of U44 (7406) and pin 15 (*DRVSEL2) is tied to pin 3 of U44.

On bottom side (trace side) of PCB cut traces on pins 10 and 15 of U49. Solder a jumper wire from pin 10 of U49 to pin 3 of U44. Solder second jumper from U15 of U49 to pin 1 of U44. External 1020 will now be configured as drive A: and internal 5 1/4 will be configured as drive B:.

Note: This modification is done at the customer's request, and will void the warranty on the A2088. Commodore will not assume any liability for this modification and no credit will be given for PCB's retured which have this modification.

Source: Commodore Techtopics 19/3-4.1

A2088 Parts List

Integrated Circuits
Position	Description	Part number	Notes
U40	Address Bus Translator	380658-01
U41	Data Bus Translator 5718	380659-01
U1	8088	380200-01
U2	8087	380201-01	Optional
U29	PAL RAM Decoder Emulator	380783-01	Produced of 16L8; PN-380219-01
U50	PAL I/O Decoder	380784-01	Produced of 16L8; PN-380219-01
U39	PAL Configuration	380785-01	Only used if jumper JA1 open
U7	FE 2010	380786-01	Vendor: Faraday
U12..U27	DRAM 256k X 1, 150 ns	380223-01
U32..U35	DRAM 64k X 4, 150 ns	380256-01
U42	FDC 9268	380787-01	Vendor: SMC
U28	BIOS PC-Emulator	380788-01	Produced of 27128 EPROM or ROM 23128 TAC = 250 ns
U10, U11	74 HCT 158	380227-04
U36, U37	74 HCT 257	380227-58
U43, U44	7406	901522-06
U45	74 LS 08	901521-03
U46	74 LS 14	901521-30
U47	74 LS 125	901521-20
U38	74 LS 133	901521-15
U48	74 LS 164	901521-28
U49	74 LS 175	901521-34
U8, U9	74 LS 244	901521-13
U3, U30, U51	74 LS 245	901521-46
U4..U6	74 LS 373	901521-29
U31	Digital Delay Line	324667-01

A2088 Connectors and jumpers

Connectors and jumpers
Position	Type	Description	Notes
J1	2x3 pin header (903345-03)	Default display jumper	Monochrome: 3-5 + 4-6, Color 40x25: 3-5 + 2-4, Color 80x25: 1-3 + 4-6, None: 1-3 + 2-4
J2	1x2 pin header (903326-02)	Speaker
J3	2x17 pin header (903345-17)	Internal Floppy Disk A:	Pin 3 removed at assembly
J4	23 pin SUB-D female (327033-01, 310975-01)	External Floppy Disk B:	Amiga-compatible
J5	2x50 cardedge	Amiga 2000 bus
J6	2x31 cardedge	PC bus
J7	1x8 pin header (903326-08)	Test connector	Pin 6 removed at assembly
JA1	Wire jumper (903781-01)
JA2	Wire jumper (903781-01)