Amstrad User Group
The Amstrad PC7486SLC.
A nice photograph (from the previous owner - the camera I used to photograph this machine was outdated and the tapes a bit worn) of the PC7486SLC, based on a less common derivative of the Intel 80486 processor, the 486SLC. The DX and SX versions are quite well known but I had never heard of the SLC before. I do not quite know whether this involves an Intel or a Cyrix product.
I do know that it involves a low-energy version of the 80486SX processor, so without the mathematical coprocessor (the SX does not have this coprocessor) or the 8 kilobytes built-in cache memory. The clock speed reported is 28mHz, so it will classify as a 33mHz 80486SX but it is a little bit of an unusual processor, I have to say that...
The brand of the Basic Input Output System (BIOS) is also less familiar. It is not a well known manufacturer like Phoenix or American Megatrends (AMI) but a company that is unknown to me: Quadtel. Apparently this firm still exists, see http://www.quadtel.com/index_flash.html, but it does not seem to make BIOS-software any more.
Fortunately, the BIOS is stored into ROM chips which avoids the troubles with floppy discs like with the earlier PC2386/65. These discs get lost or suffer from read-failures whenever you need them.
Striking with this computer is the look of the system unit: a miniature sized one that almost disappears below the monitor. This small size is ideal for those cramped for space but it is made of metal and, combined with the monitor, does not exactly qualify as a portable computer.
The machine is one of the later models in the 7000-series, was manufactured in 1993 and apparently a successor of the PC7286/7386SX because that manual is supplied and the 74876SLC is not even mentioned in the manual.
It looks to me that this computer is a collection of left-over parts along with a newer processor, gathered to form a marketable computer. You see this phenomenon more often: upgrade certain elements to sell older stock. This tactic has proven itself before. But, in spite of these negative suspicions, the computer has a very acceptable level of performance. Microsoft Windows 3.1 was supplied with the computer but has been replaced in the meantime by Windows 95. Any original software from Amstrad that came with the machine unfortunately got lost.
With 4 megabytes memory, a hard disc of 407 megabytes (13 ms average access time) and a 3.5" HD disc drive this computer has the capacity to deal with Windows 95. But the missing CD ROM player is an indication that this is an elderly type of 80486 computer.
The back of the computer, again, shows the strange proportions of the system unit when compared to the monitor. The depth is also disproportional.
The computer is equipped with two (unused) serial ports, a connection for a VGA monitor and a parallel Centronics printer port. In spite of the miniature dimensions of the system unit, the computer can still accommodate two ISA 16-bit expansion cards: half length that is.
The graphics card is, as often with Amstrad, from Paradise and the computer comes with a 14" VGA colour monitor.
The inevitable millennium problems are not immediately evident but I still have to test the machine and figure them out for Windows 95. I guess that these will only be relevant when you work with Internet or applications that depend on or use date or time. The clock in the CMOS is running correctly and showing the right time, but that does not say much about possible internal problems. Someone who uses a word processor, games or similar applications will perhaps never notice them.
I am considering to upgrade the computer with a CD Rom player and a 3" Mitsumi disc drive for exchanging data with the older Amstrad's. Unfortunately this machine is a bit too light to run the current CP/M emulator programs and the system unit is too small to house expansions internally. But it would give the machine a new life and task.
The connectors of mouse and keyboard are both of the PS/2 type. Remarkable is the location of these connections on the bottom of the computer (see the picture on the right). Besides the PS/2 connectors, the computers has 2 serial COM ports available so you still can connect some peripheral equipment.
Both the keyboard and the mouse look a little cheap and I especially do not like the keyboard in day-to-day use. A mouse may be more subject to taste and opinion but this one is not to my liking either. Too flat and square: it more or less resembles an oversized match box.
But it works and tastes may differ. And you can always replace the mouse and keyboard by other specimen. In this case, though, do note that 'always' does not apply to all Amstrad computers! Amstrad often has design elements in their hardware that cause things to be incompatible with the market standards.
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