Snow Bros. - Nick & Tom returns to the Analogue Pocket and MiSTerFPGA platforms with a major revision. Released by Toaplan in 1990, it is a single-screen platformer in which the snowman twins Nick and Tom fight through fifty stages of monsters to rescue the princesses Puripuri and Puchipuchi.
The first release got the core booting and playable on both platforms. This revision is a much deeper pass. The core now runs on the current K3 framework, its OPL2 sound is handled by the new x3812 implementation, screen flip support is added, and a number of other smaller fixes are in. What follows is a hardware overview, a rundown of what changed in this revision, and the game itself.
Overview:
Snow Bros. runs on a compact Toaplan board. A Motorola MC68000 at 8 MHz handles the game logic, inputs, sprite control, and palette, with no second processor on the main bus. Sound is driven by a Zilog Z80 at 6 MHz paired with a YM3812 (OPL2) at 3 MHz, with the Z80 taking commands from the 68000 through a bidirectional sound latch. Audio output is mono.
The video is produced entirely by Kaneko's Pandora sprite renderer, which draws the whole scene from sprites into a frame buffer rather than from tile layers. The frame buffer is double-buffered, with the Pandora rendering into the back page while the display reads the front, and the two pages swapping once per frame. The board outputs a 256x224 image at 57.444 Hz from a 6 MHz pixel clock, giving a 15.625 kHz horizontal scan rate, with a 256-entry palette in 15-bit color.
Core Updates:
The core has been rebuilt on the current K3 framework. This is the same chassis the recent releases run on, and moving Snow Bros. onto it brings a new MiSTer build alongside the Pocket one, a consistent set of OSD options, and the current loader and video path.
Sound is now handled by the new x3812 OPL2 implementation in place of the previous one, and it fixes the music tempo. The earlier OPL2 ran the soundtrack about thirteen percent slow even with the chip clocked correctly at 3 MHz. The problem was not the clock but the YM3812 timer behavior. Sample recordings of x3812 can be heard below.
The music driver leans on the chip's interrupt timer to pace the song, and the previous implementation mishandled the timer-reset write, corrupting that timing. The x3812 handles the timer and its interrupt exactly as the hardware does, so the music now plays at the correct speed.
The core is designed to run faster as well. Everything now runs synchronously off the 96 MHz master clock, with each device taking its timing from a clock enable derived from that single source.
Screen flip is implemented. The earlier release left it out and warned against turning it on, since enabling it clipped sprites at the edges. The flip now works correctly across the whole screen, and the pause overlay flips with it.
A number of smaller fixes came along with the revision. Inputs that could drop in the service menu were traced to the sound CPU and corrected, two display alignment defects were tracked down and fixed, and the cheats were reworked.
Core Options:
The MiSTer core includes the standard K3 video settings for aspect ratio, vertical scaling and cropping, scandoubler effects, and H/V positioning and sync adjustments, along with separate OPL2 audio enable and volume controls. Game settings provide per-player auto-fire with adjustable rates, mapping options for Player 1 and Player 2, and a synced mapping mode that mirrors Player 1's layout to Player 2. Arcade dip switches, including screen flip and the invulnerability switch, are directly accessible from the OSD.
Cheats are accessible from the OSD and include a starting floor select, infinite credits, infinite time, and a set of per-player options covering infinite lives, invincibility, rapid fire, and individual power-ups. A few work as expected only with that in mind: enabling Secret Bonus or Items Do Not Disappear will keep Nick and Tom from advancing to the next floor.
The Pocket core provides auto-fire with per-button targeting and adjustable rates, the relevant arcade dip switches, and a focused single-player cheat set covering the starting floor, secret bonus, item persistence, the pumpkin behavior, and a full power-up.
History, Gameplay, and Regional Information:
Snow Bros. - Nick & Tom was developed and published by Toaplan, reaching Japanese arcades in April 1990 and North America the following month, distributed there by Romstar, with a European release later in the year. The soundtrack was composed by Osamu Ohta, who had also scored Toaplan's Wardner and Twin Hawk. It was also licensed to Dooyong for distribution, one of several regional sets the board shipped in.
The gameplay is a single-screen platformer for one or two players at once. Nick and Tom clear each stage by burying its monsters in thrown snow until they are fully encased in a snowball, then rolling or kicking that snowball across the screen, where it bounces off walls and flattens anything in its path before shattering. A monster only partly covered will shake the snow off and keep moving, so the timing of the throws matters. There are fifty stages in all, with a boss waiting at every tenth.
Defeated enemies drop colored potions that adjust the brothers for a while, raising movement speed, widening the spread of the snow, or lengthening how far a snowball is thrown, and the letters that occasionally appear can be collected to spell S-N-O-W for an extra life. The goal across the climb is to rescue the twin princesses Puripuri and Puchipuchi.
Snow Bros. did well in arcades and has held a cult following since. Game Machine listed it as the eleventh most popular arcade game in Japan for June 1990, and the same placement was reported in North America, where it became a fixture of the era's beat-the-stage cooperative play.
Updates:
Files are available through update_all for MiSTerFPGA and through pupdate for the Analogue Pocket, and the release can also be downloaded directly from our GitHub at any time. Give the updaters time to sync since the core was just republished.
Now that x3812 is complete, the older Toaplan titles will be finalized for the MiSTerFPGA and PocketFPGA platforms. The next set of updated Toaplan releases will cover Flying Shark, Twin Cobra, Wardner, and Rally Bike.
Disclaimer: All product names, trademarks, and registered trademarks mentioned are the property of their respective owners. "Analogue", "Analogue Pocket", "OpenFPGA", "MiSTer", "MiSTerFPGA", "Taito", "Toaplan", "Romstar", "Dooyong", "Motorola", "Zilog", "Yamaha", "Kaneko", and all derivative works are trademarks, registered trademarks, or copyrighted materials of their respective holders. Use of these names does not imply endorsement or association with this post. All rights reserved to their respective owners. This post is for educational and research purposes only.