Epson HX-20
This article needs additional citations for verification. (April 2023) |
Seiko Epson | |
Release date | July 1982[1][2][3] |
---|---|
Introductory price | US$795 (today $2430) |
CPU | two Hitachi 6301 CPUs at 614 kHz |
Memory | 16 kB RAM expandable to 32 kB 32 kB ROM expandable to 64 kB |
Display | 4 lines x 20 characters LCD |
Graphics | 120 × 32-pixel |
Input | full-transit keyboard |
Power | rechargeable nickel-cadmium batteries |
Dimensions | A4 Sized |
Mass | approximately 1.6 kg |
The Epson HX-20 (also known as the HC-20) was the first "true"
Features
Epson advertised the HX-20 with a photograph and photo editing of the computer on
The later, more popular
Reception
LCD
The LCD is 120×32 pixels and is controlled by six μPD7227[12] LCD controller ICs each responsible for 40×16 pixels of the LCD. The μPD7227 uses a serial protocol and has two memory banks for switching between rows 0-7 and 8-15. It features multiple modes, including "Write", "Read", "AND", "OR" and "Character". The "character" mode draws characters from a built-in character map. Each bank is 40 bytes with bit 6 of the address determining the bank and even though the address can be up to 127, nothing will happen when trying to access data outside the banks. If the pointer action in a command is set to decrement and the pointer is at 0, the pointer will wrap to 127.
Monitor
The Monitor program can be accessed via the main menu on startup by pressing 1, by typing the command "MON" in BASIC or by causing a trap, i.e. writing/reading to/from protected addresses or executing an illegal instruction. In the case of a trap, "Trap!" will be displayed in the Monitor and the user can use it for debugging.
When entering Monitor it shows a prompt on the first line, "Trap!" on the second line (if entered via a trap) and the CPU
Monitor can be used for reading and writing memory, modifying CPU registers, running code at specific addresses in memory, saving/loading memory to/from a plugin option, etc. This is very useful for debugging programs written in machine code in difference to programs written in the EPSON BASIC programming language.
Commands
Command | Syntax | Description |
---|---|---|
S (Set) | S<addr> [old] [new] | Writes the 8-bit value "new" (in hex) to 16-bit address <addr>. Entering only the address and pressing enter will make the old value at the address appear and the cursor put after the old value for entering a value. |
D (Dump) | D<addr> | Dumps the values from addresses <addr> to <addr + 14> to the display. |
G (Go) | G<addr>,<breakpoint> | Sets the programme counter to the 16-bit address <addr> and will return to Monitor before the breakpoint address <breakpoint> is executed. |
X (Examine) | X | Allows the user to display and change the contents of each register. The RETURN key applies the changed value (if any) and jumps between registers. Typing a non-hexadecimal character exits this command. |
R (Read) | R<device>,<filename> | Transfer data from an external storage to memory. <device> can be any of M (microcassette), C (external cassette) and P (ROM cartridge). The memory address is specified using the "A (Address)" command. |
W (Write) | W<device>,<filename> | Transfer data from memory specified by the "A (Address)" command to an external storage. See "R (Read)" for more information. ROM cartridge is not supported by this command. |
V (Verify) | V<device>,<filename> | Verifies data transferred to an external storage against the memory specified by the "A (Address)" command. See "R (Read)" for more information. ROM cartridge is not supported by this command. |
A (Address) | A | Specify an address range for commands R, W and V. The user will be prompted with T (Top address), L (Last address), O (Offset value) and E (Entrypoint). Offset and entrypoint values are only used by the "W (Write)" and "V (Verify)" commands. |
K (Key set) | K<text> | Enter a sequence of keys to be pressed automatically on power up (and reset). Press CTRL+@ to stop. A maximum of 18 characters can be entered and function keys counts as two characters. |
B (Back) | B | Return to the procedure from which Monitor was called. |
Memory map
Start | End | Description |
---|---|---|
0000 | 001F | Internal registers |
0020 | 003F | I/O select |
0040 | 007F | RTC registers + RAM |
0080 | 3FFF | RAM |
4000 | 5FFF | Used by expansion unit |
6000 | 7FFF | ROM #4 (Option ROM) |
8000 | 9FFF | ROM #3 |
A000 | BFFF | ROM #2 |
C000 | DFFF | ROM #1 |
E000 | FFFF | ROM #0 |
ROM #0 and #1 are known as the I/O ROMs, handling system reset and providing functions for using the LCD, keyboard, clock, printer, speaker, serial communication, etc. The I/O ROMs are equivalent to the BIOS in modern PCs. ROM #0 also contains the interrupt vector table at FFF0-FFFF. FFFE-FFFF determines what the program counter should be set to on power up or reset. In the standard set of ROMs for the HX-20, this value is E000, the start of ROM #0.
ROM #2 and #3 contains the BASIC interpreter. If the BASIC ROMs are removed from the motherboard, the BASIC option in the main menu will disappear, leaving only MONITOR. This is because ROM #3 contains a program header which is detected by the menu routines. This works the same for all user-created programs, except the program type is different.
The Expansion unit added up to 16 kByte of RAM and two ROM sockets. The latter could only be used by switching off the internal BASIC ROMS.[13]
Similar Epson models
- HC-80 (Japanese version of the PX-8)
- HC-88 (Japanese version of the PX-8)
- HX-40 (American version of the PX-4)
- HX-45 (American version of the PX-4)
- KX-1
- PX-16 (IBM PC compatible portable, cartridges compatible with PX-4)
- PX-4 (successor of the HX-20, with larger screen and CP/M compatible like the PX-8)
- PX-8 (Geneva)
- EHT-30, EHT-40
See also
References
- ^ a b c d "Shinshu Seiki/Suwa Seikosha HC-20". IPSJ Computer Museum. Retrieved 19 June 2019.
- ^ a b c Michael R. Peres, The Focal Encyclopedia of Photography, page 306, Taylor & Francis
- ^ "Epson HX-20 laptop computer". Museum of Technology. Retrieved 9 September 2016.
- ^ "Epson SX-20 Promotional Brochure" (PDF). Epson America, Inc. 1987. Retrieved 2 November 2008.
- ^ FR2487094A1 patent: Notebook computer system small
- ^ Epson HX-20, Old Computers
- ^ Advertisement (December 1982). "Actual size". BYTE. pp. 260–261. Retrieved 19 October 2013.
- ^ a b c d e f g h i j HX-20 Operations Manual
- ^ jrok.om - Replacement CUS60, CUS63 and some CUS64
- ^ "C-20 PROTOCOL". 19 November 1982. Retrieved 19 June 2019.
- ^ Ramsey, David (September 1983). "Epson's HX-20 and Texas Instruments' CC-40". BYTE. p. 193. Retrieved 20 October 2013.
- ^ "NEC Electronics Inc. μPD7227 COMS, Intelligent, Dot Matrix LCD Controller/Drive" (PDF). Retrieved 2024-02-12.
- ^ Technical Support Document number 72a Archived 2018-09-25 at the Wayback Machine, Using the Epson HX-20 expansion unit
External links
- Epson HX-20 documentation, photos and software
- Epson's HX-20 manual and additional material
- HX-20 utility and game programs
- 'HXTape' program to read and write tapes via a soundcard
- old-computers.com article on the HX-20 Archived 2010-03-30 at the Wayback Machine
- 1983 Epson HX-20 computer., (evaluation) David H. Ahl., CREATIVE COMPUTING VOL. 9, NO. 3 / MARCH 1983 / PAGE 101
- vintage-computer.com article about the HX-20
- https://www.youtube.com/watch?v=o-F_hL1bZsw The World's First Laptop - Epson HX-20 / HC-20