Ampro Corporation 486E Solid State Disk (SSD) Drives, Accessing the Byte-Wide Socket

Little Board™/486e Technical Manual

2–50

Executing programs directly from the byte-wide socket can adversely affect system performance.

There are a number of factors that can contribute to the performance impact:

! The byte-wide device is substantially slowe r than DRA M, a s it i s an 8-bi t d evice inste ad of 32-

bit device.

! The device is accessed from the PC expansion bus, which is much slower than the high-speed

processor memory bus.

Performance can be substantially improved by copying the contents of the byte-wide device into

RAM and executing directly from RAM.

Solid State Disk (SSD) Drives

Using the Ampro Solid State Disk (SSD) Suppo rt So f tware, y ou c an co nfig ure E PROM , Fla sh

EPROM, or SRAM solid-state devices, installed in the byte-wide sockets, to act as one or more disk

drives. No custom programming is required. Regular DOS-comp liant pr ogra ms, inc luding stan dard

DOS utilities, can be used without modification.

Ampro’s SSD support software creates data image files, based on your application programs and

operating system, which can be programmed into the devices you install in the byte-wide sockets.

The Ampro ROM-BIOS treats these devices like one or more disk drives, loading the programs into

DRAM for execution. The sockets can be combined to serve as a single drive, or each socket can be

used as a separate drive. You can use SSD drives in addition to, or instead of, normal floppy and

hard disk drives.

You can increase system SSD capacity by adding one or more of Ampro’s SSD expansion modules.

Accessing the Byte-Wide Socket

To access the byte-wide socket, it must be enabled. Using SETUP, either device can be enabled at

boot time. This places the contents of the enabled device at the address specified in SETUP and the

processor can access this memory in a normal fashion.

Here is a simple assembly language routine showin g how to use an Amp ro ex tend ed-BIO S call to

enable or disable the byte-wide memory socket, S0. This code selects the first 64K page on large

devices.

;----------------------------------------------------------

; Access control code for a byte-wide socket

;----------------------------------------------------------

MOV AH,0CDH ; AMPRO function call

MOV AL,03h ; Use 03 for S0

MOV BL,nn ; Use 01 to turn ON or 00 to turn OFF

MOV BH,00 ; Selects page 0 of the device

INT 13H

Table 2–37 lists the segment addressing in large memory devices.