 Acer File Extensions |
Acer A1 Motherboard
Jumper and Connector Layout
Note - The blackened pin of a jumper represents pin 1.
Overview
The following lists the major features of the Acer A1 system:
- 486SX, DX or DX2-series CPU
- 4-MB on-board RAM expandable to 36-MB
- two 72-pin SIMM sockets for memory upgrade
- 120-pin connector for ISA raiser card
- 128-KB ROM for system BIOS and VGA BIOS
- optional on-board cache memory (64-KB, 128-KB or 256-KB)
- system clock/calendar
- two 9-pin serial ports
- one 25-pin Centronics parallel port
- 512-KB or 1-MB DRAM for ultra-VGA interface, expandable to 1 or 2 MB
- embedded hard disk interface
- One PS/2-compatible keyboard port
- One PS/2-compatible mouse port
Jumper Settings
| Jumper | Setting | Function |
|---|---|---|
| JP1 | OPEN | ACER BIOS |
| CLOSED | OEM BIOS | |
| JP2 | 1-2 | Enable Password (Security) |
| 2-3 | Disable Password (Security) | |
| JP4 | 1-2 | Flash ROM |
| 2-3 | EPROM | |
| JP5 | 1-2 | Normal Floppy |
| 2-3 | 3Mode Floppy | |
| *JP7 | 1-2 | 33MHz |
| 2-3 | 25MHz | |
| *CN14 | 3-7 | 33MHz (DX2/66) |
| 4-8 | 25MHz (DX2/50) | |
| * You need to set only one jumper, either CN14 or JP7 to select the CPU clock speed. | ||
| JP14 | CLOSE | Enable On-Board VGA |
| OPEN | Disable On-Board VGA | |
| JP19 | CLOSE | Debug Jumper (Always Closed) |
| JP22 | OPEN | Lock Key |
| CLOSED | Unlock key | |
| JP28 | 1-2 | Enable On-Board Memory |
| 2-3 | Disable On-Board Memory or No On-Board Memory | |
System CPU Clock Selection
| CPU Clock | JP7 | JP8 | JP9 | JP10 | JP17 |
|---|---|---|---|---|---|
| 25MHz (DX2/50) | 2-3 | 2-3 | 1-2 | 2-3 | 2-3 |
| 33MHz (DX2/66) | 1-2 | 2-3 | 1-2 | 2-3 | 2-3 |
| 40MHz | 1-2 | 1-2 | 2-3 | 1-2 | 1-2 |
| 50MHz | 2-3 | 2-3 | 1-2 | 1-2 | 1-2 |
CPU Type Selection
| CPU Type | JP11 | JP12 | JP13 | JP15 | JP18 | JP20 | JP27 |
|---|---|---|---|---|---|---|---|
| 486 | 1-2 | 1-2 | 1-2 | 1-2 | 2-3 | 2-3 | OPEN |
Memory
The system board has two SIMM sockets that accept 4-MB, 8-MB, or 16-MB SIMMs, upto a maximum of 32MB (or 36MB if motherboard has 4MB on-board). 72 Pin, 70ns, Parity, Fast Page Mode SIMMS with gold tips recommended.
Cache RAM Upgrade Path
| Cache Size | SRAM Type | Location | JP24 | JP25 | JP26 |
|---|---|---|---|---|---|
| 64KB | 8K X 8 X 9 PCS | TAG, U56 TO U63 | OPEN | OPEN | 2-3 |
| 128KB | 32K X 8 X 5 PCS | TAG, U56,U58,U60,U62 | OPEN | CLOSED | 1-2 |
| 256KB | 32K X 8 X 9 PCS | TAG, U56 TO U63 | CLOSED | CLOSED | 2-3 |
Upgrade Video Memory
You can increase VGA RAM to 1 or 2 MB.
To upgrade the VGA RAM, do the following:
1. To upgrade from 512 to 1MB, order p/n 91.00023.901 from Acer Access. To upgrade from 1MB to 2MB order p/n 02.54260.030.
2. Locate the VGA memory expansion sockets on the system board labelled U12, U13, U15 and U16.
3. Gently but firmly insert a 44256 DRAM (256 K bit by 4, 70-ns) chip into each of the VGA memory expansion sockets.
Increasing VGA memory up to 2 MB is an option available to you. To do this, insert two 51460 (256 K bit by 16) DRAM chips on the sockets labelled U10 and U9.