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Sharp HB-8000
This page was last modified 19:06, 30 June 2021 by Mars2000you. Based on work by Rderooy and Gdx and others.

Contents

Description

The HB-8000 is a computer released on the Brazilian market by Sharp (Epcom). The computer consists out of a single unit with integrated keyboard and power supply. HB means 'Hotbit' (Probably this name alludes to Hit-Bit MSX from Sony).

Only one model called HB-8000 was produced in four case versions: versions 1.0 and 1.1 have a white/gray top case with black bottom case. The original 1.0 model is very rare as most of them were upgraded to 1.1 for free at the first opportunity they were brought to be serviced, apparently because an accented characters issues.

There was a batch of white HB-8000 with ROM 1.2 and paintings on the top, and the last version with ROM 1.2 has an all black case, and some leftovers from a failed attempt to produce a Brazilian MSX2.

The slot and arrow keys format and arrangement shows some similarity to Canon MSX models, especially the Canon V-20.

Though the Hotbit followed MSX standards strictly unlike the competing Gradiente Expert, it did not win the marketing battle, and its production was stopped in 1988. There are never-confirmed rumours that Japanese Sharp is behind the production stop.

The units were shipped with: 2 Polys, cardboard spacer, BASIC manual, User manual, a folder with technical assistance providers, RF Cable with RCA connectors, MSX/TV RF antenna selector box with 75/300 ohm BALUN for use with a TV set, tape recorder cable, and a cassete called "INTRODUÇÃO AO HOTBIT" with demonstration software.

As a part of the promotional campaign for the HB-8000, an audio track was recorded, and a promotional vinyl was sent to the home of the people by mass-mailing. In this track we can listen that "Hotbit is the microcomputer of Epcom". Sharp and MSX are not mentioned.

Sharp/Epcom released some peripherals to be used with Hotbits, with the colors of the white version - see the Sharp (Epcom) page.

Brand Sharp
Model HB-8000
Year 1985
Region Brazil
Launch price
RAM 64kB (in slot 3)
VRAM 16kB
Media Cartridges
Video Texas Instruments TMS9128NL
Audio PSG (YM2149 or AY-3-8910)
Chipset none (separate IC's)
Keyboard layout QWERTY with a "ç" key
Extras Power supply outlet for accessories, reset button, demo cassette
Emulation ROM for the v1.1 and v1.2 dumped and emulated. For v1.0 a ROM dump is needed. See this thread for details

Pictures

Sharp HB-8000 white, version 1
Sharp HB-8000 white, version 2
Sharp HB-8000 white, version 3
Sharp HB-8000 black
Sharp HB-8000 inside box
Sharp HB-8000 inside
Sharp HB-8000 box, version 1
Sharp HB-8000 box, version 2
Sharp HB-8000 box, black version
Sharp HB-8000 demo tape
Sharp HB-8000 BASIC manual
Sharp HB-8000 USER manual
Sharp HB-8000 Black USER manual
Sharp HB-8000 black box (detail)
Sharp HB-8000 back
Sharp HB-8000 label

Specifications

The Sharp HB-8000 is a MSX1 computer, with 64kB RAM, a Z80A from Zilog and two cartridge slots, one at the top and another on the left side of the system, under a removable cover.

For storage, it can optionally use a tape recorder (standard 1200/2400 bps) or up to two external 5¼" disk drives (360 kB) using a Sharp HB-3600 disk controller.

Slot Map

Slot 0 Slot 1 Slot 2 Slot 3
Page C000h~FFFFh Cartridge
Slot 1 		Cartridge
Slot 2 		64kB
RAM
Page 8000h~BFFFh
Page 4000h~7FFFh Main-ROM
Page 0000h~3FFFh

Connections

Features

Good/strong features

  • One switched electrical AC sockets are provided.
  • Reset button (located at bottom left side)
  • Just as in almost every Brazilian electronic appliance, the power supply has a selector switch for 120/240 VAC, this way the unit can be used in places with mains of either 110~127VAC or 220~240VAC.

Bad/weak features

  • Second external slot don't have protection from inserting cartridges with the computer turned on.
  • The internal power supply don't have enough juice to power several devices at the same time.

Versions

  • White HB-8000 with ROM 1.0 (1st version)

The first units were shipped without the MSX Logo over the DEL key, and without the black MSX Sticker at the box.

A small difference in the ASCII table between both 1.0 ROM versions of Expert XP-800 and Hotbit 1.0 caused accented character issues for users in Brazil. Algo creating trouble for software developers and printer manufacturers. This was fixed replacing the Main-ROM by a new version which is the ROM of Hotbit HB-8000 1.1.

Due to this issue, most of Hotbits 1.0 undergone a recall to replace their original 1.0 ROMs by the 1.1 version. The 1.0 Version from HB-8000 ROM is now so rare that is yet to be dumped, and no known emulator has this machine emulated.

  • White HB-8000 with ROM 1.1 (2nd version)

This units have the MSX Logo over the DEL key, and a sticker on the box with a black MSX logo. At some point, Sharp started to include a second cassete tape called "A013 - CURSO DE BASIC", and to indicate this, added a red sticker on the box. Some of this units can be found with the ROM 1.2, but it is unknown if they were shipped that way, or upgraded by technical assistance, or even by the users.

  • White HB-8000 with ROM 1.2 (3rd version)

After developing the ROM version 1.2, Sharp shipped a small batch of white computers with a different painting on the top of the case. As this version has the logo of EPCOM, it's believed that it's the very first version of the case, for the HB-8000 prototype, and maybe Sharp decided to use all the white cases left on the stock before starting to ship the next version with all-black cases. This version is considered rare.

  • Black HB-8000 with ROM 1.2

In this version, the case is all-black, and there is a sticker at the top saying the machine has 64Kb of RAM. The USER manual was replaced by a smaller one, while the BASIC manual remained the same. At the box, now with the MSX logo printed, there is a picture of a black HB-3600 floppy disk drive unit, which was never launched at the market. None of the Sharp MSX peripherals had a black version. Inside the bottom case there is a place for a battery holder, and the back panel was covered with a plastic plate to hide a larger hole for a DIN8 RGB connector. These cases were intended to be used on a never released MSX2 version.

Timing Issues

The 1.2 ROM version has a issue with the PLAY command on BASIC; This command counts JIFFY increments to determine how much time a note should be PLAYed. On this specific ROM version, it counts less JIFFY increments than it should on a 60Hz interrupt machine, so the PLAY string plays faster (without pitch shifting issues).

Hardware

The power supply is linear, based on LM723 voltage regulator. There is a signal from the switch at the cover of the slot 1 for power supply shutdown when a cartridge is being inserted. There is also a crowbar protection, with a fuse on the +5VDC line. The PCB is the same for all versions.

There are three revisions for the main PCB, with some differences in the audio output circuit. The revisions 1 and 2 have a 6-pin connector to the video/RF PCB, and there is a shielded jumper underside the PCBs connecting the clock of the system to the video/RF PCB of revision 1. The main PCB of revision 3 has a 7-pin connector to the video/RF PCB of revision 2. This extra pin is for the clock, this way eliminating the jumper.

In this PCB there are a set of jumpers:

  • P1 - Open. If closed, activates the /BUSRQ signal on the Z80.
  • P2 - Open. If closed, disable the data and address buffers of the Z80.
  • P3 - Normally at 1-3 and 2-4. If switched to 1-5 and 2-6, exchanges the selection of slots 0 and 1, thus enabling you to put a 32Kb ROM with different BIOS + BASIC at slot 1. The two jumpers must be changed together or else you will short the outputs of 74LS139 marked as CI-14.

The video/RF PCB is based on LM1889N. There are two revisions of this PCB. Revision 1 has a 6-pin connector to be used with main PCB of revisions 1 and 2. Revision 2 PCB has a 7-pin connector and is to be used with main PCB revision 3.

Links

All of scanned material is in Brazilian Portuguese:

Videos

All on YouTube

Retrieved from "https://www.msx.org/wiki/Sharp_HB-8000"