Sharp PC-5000 — voidstar

Acquired April 2023 – WORK IN PROGRESS (TBD)

Introduction

The first “clamshell” design laptop was the GRiD Compass released in April 1982, using an Intel 8086 CPU, selling for $8,150 (ads claim GRiD had their own in-house operating system, but also supported MS-DOS 2.0). It was expensive due to use of the 320×240 plasma screen and bubble memory. There is a report that GRiD patented/copyrighted this design, but that design was not enforced until GRiD later sold the patent to Tandy.

In November 1983, Sharp released a somewhat similar system called the PC-5000. This had a less expensive 640×80 LCD (no backlight) and 128KB bubble memory cartridges, using an Intel 8088 CPU at 4.77 MHz running MS-DOS 2.0. This was primarily sold in Japan, Europe (Germany, France), and UK markets, but was available in the US for about $2000 (until about 1985, which then the Sharp PC-7000 was released).

A main unique feature of the Sharp PC-5000 was the attachable full-page (8.5″x11″) line printer, that used a “thermal head” and didn’t rely on liquid ink (see here). The PC-5000 is also one of the only few systems to have bootable “bubble memory” as a read/write media. Bubble memory cartridges are like a very early version of Compact Flash (CF) cards, where CF didn’t become popular until over a decade later.

CATEGORY 1 IMAGES: Bottom of unit

There are several interesting things to note on the bottom of the system.

Large speaker grills (both at the bottom and on the side), suggesting a desire for the audio out of this system to be well heard. The built in BASIC includes a BEEP, SOUND, and PLAY commands.
The tiny switch is related to the CLOCK. (TBD, it is mentioned in the user manual)
Of the two panels, one is for RAM expansion and the other is for built-in ROM extensions. The manual directly suggests the use of a coin to open these panels. One panel is shorter than the other only because the volume and contrast knobs are there along the side (an unfortunate design compromise, to keep things compact).
There is a panel of text indicating the system is Made in Japan, then also lists a couple of patents. Both patents appear to be related to the LCD display, and not the design of the system itself (such as the use of clamshell folding or bubble memory).
The screws at top secure the printer in place.

US PATENT 3902169
(Drive system for liquid crystal display units; origins c. 1972, expired in 1992)
US PATENT 3976994
(Liquid crystal display system; origins c. 1973, expired 1993)

CATEGORY 2 IMAGES: Bottom panel cartridges (ROM and RAM)

On the back of these modules, there is a small screw – so these can probably be easily opened.

CATEGORY 3 IMAGES: Various exterior shots

The 24-pin RS232C port works as expected with a modern WiModem232.

The 37-pin external bus has so far been more nebulous. This should be quite similar to the 37-pin external bus of the IBM PC 5150, but so far no luck getting an external disk drive attached to this system.

So far, I haven’t found a use for the tape cassette interface. The built in BASIC actually doesn’t support a SAVE option to save to tape (which is interesting because I think the IBM PC 5150 and XT, that built in BASIC had no option to save BASIC programs to disks).

The battery is some LEAD battery.

CATEGORY 4 IMAGES: Interesting notes

From the manual, the BASIC DRAW command uses a Microsoft “language” called GMI/GML.

Disk Drive Support Notes

I’ve started a discussion here to try to determine a modern solution to use as a disk drive for the PC-5000. But as a summary:

The PC-5000 uses the 5.25″ dual disk drive system model CE-510F
That same disk drive we think was also used on the Sharp MZ-series (e.g. MZ-80B)
Online images of an opened CE-510F showed the following part: “TEAC 14733730 10” which we think was used in the FD55 disk drive.

U.S. Advertisements

I haven’t yet come across the PC-5000 advertised in PC Magazine, but I didn’t find several references mentioned in BYTE Magazine.

BELOW: BYTE magazine – December 1983 pg342