Minimig (a
portmanteau
In linguistics, a blend—also known as a blend word, lexical blend, or portmanteau—is a word formed by combining the meanings, and parts of the sounds, of two or more words together. of ''Mini Amiga'') is an open source re-implementation of an
Amiga 500
The Amiga 500, also known as the A500, was the first popular version of the Amiga home computer, "redefining the home computer market and making so-called luxury features such as multitasking and colour a standard long before Microsoft or Apple ...
using a
field-programmable gate array (FPGA).
Minimig started around January 2005 as a proof of concept by Dutch electrical engineer Dennis van Weeren. He intended Minimig as the answer to the ongoing discussions within the Amiga community on implementing the
Amiga custom chipset using an FPGA. The project's source code and schematics were released under version 3 of the
GNU General Public Licence
The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or copyleft, ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was th ...
on 25 July 2007.
Original prototype
The original Minimig prototype is based on the Xilinx Spartan-3 Starter Kit, the
Original Amiga Chipset is synthesized in the FPGA. Two printed circuit boards are attached via the FPGA kit expansion ports. The first one holds a 3.3V Motorola 68000-type CPU. The second has a
MultiMediaCard
MultiMediaCard, officially abbreviated as MMC, is a memory card standard used for solid-state storage. Unveiled in 1997 by SanDisk and Siemens, MMC is based on a surface-contact low-pin-count serial interface using a single memory stack subs ...
slot with a small PIC microcontroller acting as a disc controller that supports the
FAT16
File Allocation Table (FAT) is a file system developed for personal computers and was the default file system for the MS-DOS and Windows 9x operating systems. Originally developed in 1977 for use on floppy disks, it was adapted for use on Ha ...
filesystem and does on-the-fly
Amiga disk file (ADF) decoding.
VGA-+-PS2 (joystick etc.)
,
CPU <-> FPGA <-> Microcontroller <-> Flashmemory
,
RAM
The prototype was shown at an Amiga meet and loaded most Amiga programs, with some bugs. This prototype used
verilog
Verilog, standardized as IEEE 1364, is a hardware description language (HDL) used to model electronic systems. It is most commonly used in the design and verification of digital circuits, with the highest level of abstraction being at the re ...
instead of
VHDL
VHDL (Very High Speed Integrated Circuit Program, VHSIC Hardware Description Language) is a hardware description language that can model the behavior and structure of Digital electronics, digital systems at multiple levels of abstraction, ran ...
on a PC using Xilinx Webpack software for code development.
Hardware
Platform
As of Minimig rev1.0 board:
*
Xilinx Spartan-3 400k gate (XC3S400-4PQ208C) FPGA using 82% capacity.
*
Freescale
Freescale Semiconductor, Inc. was an American semiconductor manufacturer. It was created by the divestiture of the Semiconductor Products Sector of Motorola in 2004. Freescale focused their integrated circuit products on the automotive, embedde ...
MC68SEC000, 3.3V, at However, there's no MOVE sr,
is privileged and there is no real replacement instruction.
* Amiga Chip RAM bus and Slow RAM merged into a single synchronous bus running at
* 2 MB 70 ns asynchronous SRAM organised as banks.
* MCU PIC 18LF252-I/SP (An alternative is Atmel AVR
AVR is a family of microcontrollers developed since 1996 by Atmel, acquired by Microchip Technology in 2016. They are 8-bit RISC single-chip microcontrollers based on a modified Harvard architecture. AVR was one of the first microcontroller ...
) implements a FAT16 disk layout and handles loading of FPGA configuration and Kickstart. This simulates a floppy disk
A floppy disk or floppy diskette (casually referred to as a floppy, a diskette, or a disk) is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a ...
to the Amiga by encoding on the fly from ADF files.
* MMC Flash memory card to load FPGA configuration, kickstart and software for the implemented computer.
* 3× LEDs to display the disk activity, main power, and Amiga power-up status. Amiga power-up status led will also change intensity to show audio filter status.
* Video D/A consists of 4 resistors for each color red, green, blue (4 bits/color), and output via VGA connector.
* Audio from an 8 bit dithering sigma-delta converter with 2nd order analogue filter.
* +5V DC main power (~200 mA).
Ports
* Spare 3x generic I/O from the FPGA ( GPIO)
* JTAG for programming chips (TMS, TDI, TDO, TCK)
* RS232
In telecommunications, RS-232 or Recommended Standard 232 is a standard introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such as a compu ...
serial port
* 2x Joystick
A joystick, sometimes called a flight stick, is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. Also known as the control column, it is the principal control devic ...
of Atari 2600
The Atari 2600 is a home video game console developed and produced by Atari, Inc. Released in September 1977 as the Atari Video Computer System (Atari VCS), it popularized microprocessor-based hardware and games stored on swappable ROM cartridg ...
DE9M type.
* DE15F VGA video (which can output PAL-compatible signals to connect to SCART
SCART (also known as or , especially in France, 21-pin EuroSCART in marketing by Sharp Corporation, Sharp in Asia, Euroconector in Spain, EuroAV or EXT, or EIA Multiport in the United States, as an EIA interface) is a French-originated standard ...
).
* MMC Flash memory card slot.
* PS/2 connector Keyboard + Mouse
* 3.5 mm audio jack
* +5V DC 2.1 mm cylindrical DC plug power supply inlet.
Implementation
* Motorola 68000
The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Sector ...
type CPU.
* Hardware OCS and ECS, PAL
Phase Alternating Line (PAL) is a color encoding system for analog television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...
& NTSC
NTSC (from National Television System Committee) is the first American standard for analog television, published and adopted in 1941. In 1961, it was assigned the designation System M. It is also known as EIA standard 170.
In 1953, a second ...
video switchable via OSD.
* 512 KB SRAM for Kickstart used as ROM
Rom, or ROM may refer to:
Biomechanics and medicine
* Risk of mortality, a medical classification to estimate the likelihood of death for a patient
* Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac
* ...
.
* Slow RAM expansion (originally 512 KB).
* Chip RAM (originally 1024 KB).
* On-screen display offers selection of ADF disk images from the SD/MMC card using the keyboard or a joystick.
Roadmap
Issues
* It lacks a binary copy of the AmigaOS kickstart ROM from a real or free re-implementation like AROS-68k which is not yet fully compatible.
* The current firmware
In computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, h ...
for loading ROM and floppy images is limited to a single root directory and 8.3 filenames.
Development tools used
Computer: Shuttle barebone, Prescott Pentium 4
Pentium 4 is a series of single-core central processing unit, CPUs for Desktop computer, desktops, laptops and entry-level Server (computing), servers manufactured by Intel. The processors were shipped from November 20, 2000 until August 8, 20 ...
(, ) , .
Software: Xilinx
Xilinx, Inc. ( ) was an American technology and semiconductor company that primarily supplied programmable logic devices. The company is renowned for inventing the first commercially viable field-programmable gate array (FPGA). It also pioneered ...
Webpack
Webpack is a free and open-source module bundler for JavaScript. It is made primarily for JavaScript, but it can transform front-end assets such as HTML, CSS, and images if the corresponding loaders are included. Webpack takes modules with depend ...
version 6.3.03i (2007-07-22 9.1). Time from HDL source to loadable configuration file (.bit) = CPU cache
A CPU cache is a hardware cache used by the central processing unit (CPU) of a computer to reduce the average cost (time or energy) to access data from the main memory. A cache is a smaller, faster memory, located closer to a processor core, whi ...
and memory speed is vital for the Synthesis + Place & Route Silicon compiler
A silicon compiler is an electronic design automation software system, software tool that is used for high-level synthesis of integrated circuits. Such a tool takes a user's specification of an Integrated circuit design, IC design as input and auto ...
in FPGA generation software.
Future
Possible future developments include:
* A faster CPU, ECS chipset, AGA graphics (new FPGA board is required), hard disk, ethernet, small RISC-Core for enhanced AROS functions, etc.
* Use of a free kickstart replacement (e.g. AROS).
* A networked version would eliminate the need for swapping flash memories.
Upgrades
Read/write support
On 3 September 2008, a new FPGA core enables read/write support, as well as some chipset improvements.[ 090629 amiga.org]
ARM controller board upgrade
On 22 December 2008, a replacement board that fits in the PIC ( MCU) controller socket were announced. It makes hard drive, 4x floppy disk and write support possible.[ 090629 amiga.org] The FPGA core is the same for the new ARM and PIC firmware but only the ARM has enough resources to support four drives. The PIC only supports two. The upgrade also allows an increase of the CPU speed from 7.09 to 49.63 MHz with a 4 KB zero wait state CPU cache. However, it requires an FPGA core to actually carry it out (which works with the 16 MHz 68SEC000 chips).[ 090629 youtube.com]
The hard drive support is available by a virtual A600/ A1200 style GAYLE parallel ATA
Parallel ATA (PATA), originally , also known as Integrated Drive Electronics (IDE), is a standard interface designed for IBM PC-compatible computers. It was first developed by Western Digital and Compaq in 1986 for compatible hard drives and C ...
interface. Up to 551 KB/s[ 090629 amiga.org]
USB peripherals and MIDI
The Minimig port for the MiST board supports USB peripherals including USB keyboard and USB mouse as well as a physical MIDI interface.
Additional 2 MB RAM
On 22 December 2008, a modification of the original PCB by piggybacking another set of SRAM chips enables up to 4 MiB of RAM in total.
AGA support
The Minimig port for the MIST board was updated to support major AGA features allowing it to run many AGA games. A binary release, as well as the full source code, is available under GPL.
An unreleased Minimig core has been upgraded with AGA support and extended to support at least 50 MiB of Chip memory on the prototype Replay board designed by Mike Johnson at FPGA Arcade.
Similar projects
Jeri Ellsworth, who designed the C64 Direct-to-TV ''Commodore 64
The Commodore 64, also known as the C64, is an 8-bit computing, 8-bit home computer introduced in January 1982 by Commodore International (first shown at the Consumer Electronics Show, January 7–10, 1982, in Las Vegas). It has been listed in ...
on a chip'' ASIC
An application-specific integrated circuit (ASIC ) is an integrated circuit (IC) chip customized for a particular use, rather than intended for general-purpose use, such as a chip designed to run in a digital voice recorder or a high-efficien ...
, had a working Amiga on a chip prototype in 2003. Except for the 68000 processor and disk interface, everything was emulated inside a FPGA. However, the project was never finished or turned into an ASIC.
Illuwatar, a small private hardware designer in Sweden, implemented a Mini-ITX
Mini-ITX is a motherboard form factor developed by VIA Technologies in 2001. Mini-ITX motherboards have been traditionally used in small-configured computer systems. Originally, Mini-ITX was a niche standard designed for fanless cooling with a ...
form factor version of the Minimig under the Open Source design License. This hardware version fits in standard Mini-ITX cases and has dimensions of 17 cm x 17 cm. Connecting ports in this version were moved to the back of the mainboard to comply with Mini-ITX requirements.
On 9 Feb 2008 ACube Systems announced the availability of finished Minimig v1.1 boards.
On 2006-10-11 Jens Schönfeld at Individual Computers revealed that they had been working on a commercial Amiga-in-FPGA for the past year called " Clone-A" that is similar to Minimig. In contrast to Minimig, Individual Computers's Clone-A was developed by a three-person development team employing a powerful logic analyzer. The system intends to use clone chips to replace CIAs, Paula, Gary, Agnus and Denise, and the CPU will be the original from Motorola. Final chips will also include AGA and a working parallel port to enable 4-player games. Still unreleased since 2015.
Wolfgang Förster has completed the Suska project, which is an Atari ST
Atari ST is a line of personal computers from Atari Corporation and the successor to the company's Atari 8-bit computers, 8-bit computers. The initial model, the Atari 520ST, had limited release in April–June 1985, and was widely available i ...
-on-FPGA.
Inspired by Minimig, Till Harbaum invented MIST, an open FPGA based implementation of Atari ST and Amiga intended to have a low price and be easy built at home. Different than Minimig, the 68000 CPU is not present as physical device but implemented inside the FPGA.
Inspired by MIST, Alexey Melnikov invented MiSTer
''Mister'', usually written in its contracted form ''Mr.'' (American English) or ''Mr'' (British English), is a commonly used English honorific for men without a higher honorific, or professional title, or any of various designations of office. ...
,
References
External links
Source code at Google Code
Project home page (Offline)
Official Discussion Forum
{{Amiga hardware
Home computer remakes
Amiga
Computer-related introductions in 2006
Open computers